US2215295A - Surface insulation for magnetic sheet steel - Google Patents
Surface insulation for magnetic sheet steel Download PDFInfo
- Publication number
- US2215295A US2215295A US79941A US7994136A US2215295A US 2215295 A US2215295 A US 2215295A US 79941 A US79941 A US 79941A US 7994136 A US7994136 A US 7994136A US 2215295 A US2215295 A US 2215295A
- Authority
- US
- United States
- Prior art keywords
- vermiculite
- steel
- coating
- sheet steel
- water
- 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 - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/24—Magnetic cores
- H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented
-
- 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
- H01F41/0233—Manufacturing of magnetic circuits made from sheets
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/90—Magnetic feature
Definitions
- expanded vermiculite which is an aluminum-magnesium silicate sold under 25 the trade name Zonolite
- the expanded material is obtained by introducing crude vermiculite into an expansion furnace heated at about 2000 F. This results in the production of a honeycombed 30 brittle granule which immediate cooling toughens into a durable aggregate in a manner well known inthe art.
- the mixing of the water and expanded vermiculite is effected by grinding the vermiculite and water mixture until the ver- 35 miculite is in an extremely finely divided state producing a suspension of vermiculite in water and having about the consistency of house paint. This condition may be obtained by ball milling the water vermiculite mixture for about 20 to 24,
- the vermiculite initially being capable of passing through a 60 mesh screen.
- the particles of vermiculite after mixing in the ball mill are in the form of small leaves or fiat crystals.
- the water-vermiculite mixture thus prepared 45 is in effect a paint in which water is the vehicle instead of oil. It may be applied to sheet steel by means of a brush, spray, or rubber rolls and then dried in an oven at a temperature suinciently high to evaporate the water.
- the coated 50 sheets may be annealed in the usual manner, i. e.,
- the water vermiculite coating applied to silicon steel laminations as heretofore 55 pointed out provides a high degree of insulation between successive laminations andappears to give a relatively small reduction in total watt loss, i. e., up to about 2.5% as compared with laminated sheets having a core plate enamel coating. This reduction in watt loss is possibly due to the fact-that the coating prevents excessive oxidation of the sheet steel. Furthermore, the coating prevents sticking together of the steel sheets during the annealing process.
- vermiculite forms a very tight coating which cannot be rubbed off the steel or removed any easier than the regular anneal scale and gives a surface insulation resistance which is greater in both air and hot oil than that which can be obtained with core plate enamel heretofore employed in transformer construction.
- vermiculite insulation forms a very thin film coating and causes no appreciable increase in the space factor permissible in transformer construction.
- the vermiculite during the annealing process, apparently combines with the natural scale formation on the steel thereby providing a highly insulating coat. vermiculite, however, even without the assistance of the steel scale is a particularly efilcient insulator due to its leafing action.
- vermiculite While I prefer to employ a mixture of about 20 parts vermiculite and about 100 parts of water, these quantities are not critical and may be varied widely. Also, instead of employing water, I may mix the vermiculite with Water solutions which may be beneficial to the steel. Although I prefer to employ a mixture of vermiculite and water, I may employ instead of the vermiculite other materials having approximately the same chemical analysis or crystallographic form.
- the method of electrically insulating sheet steel which comprises applying to the steel a film consisting of a mixture of water and expanded vermiculite, drying the mixture to evaporatethe water and baking the vermiculite onto the steel during an anneal.
- Silicon steel sheets suitable for use in transformer laminations said sheets having an electrically insulating film thereon, said film consisting substantially of vermiculite baked thereon.
- Annealed silicon steel having a coating thereon, said coating consisting of vermiculite bonded to the natural scale formation of the steel.
- Annealed silicon steel having a coating thereon, said coating consisting of vermiculite bonded to the natural scale formation of the steel, said coating being free from alkaline bonding ma- 10 terial.
- Siliconsteel having a thin, tight, insulating coating thereon, said coating consisting substantially of vermiculitebonded to said steel and having the property of preventing sticking and excessive oxidation during anneal and causing no appreciable increase in the space factor when the coated steel is employed as laminations in transformer cores.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Treatment Of Metals (AREA)
- Paints Or Removers (AREA)
- Soft Magnetic Materials (AREA)
Description
Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE SURFACE INSULATION FOR MAGNETIC SHEET STEEL Weston Morrill, Pittsfield, Mass., assignor to General Electric Company, a corporation of New The present invention relates to the use of insulated coatings on sheet steel and more particularly to the use of very thin inorganic coatings adapted for use on transformer laminations.
Prior to the present invention, it has been customary in the construction of laminated transformer cores to coat thesheet steel laminations after anneal with a core plate enamel to provide a .suitable space relation between the laminated sheets.
It is one of the objects of the presentinvention to provide an inexpensive insulation coating on sheet steel which is suitable for use on transformer laminations and may be applied to the laminations before annealing. It is also an object of my invention to provide an insulating coating which not only has the ability to so insulate the surface of the steel that the use of a core plate enamel may be eliminated but also 0 the ability to prevent the laminations from sticking together during the annealing process.
In carrying out my invention, I mix about 20 parts by weight of expanded vermiculite, which is an aluminum-magnesium silicate sold under 25 the trade name Zonolite, with about 100 parts by weight of water. The expanded material is obtained by introducing crude vermiculite into an expansion furnace heated at about 2000 F. This results in the production of a honeycombed 30 brittle granule which immediate cooling toughens into a durable aggregate in a manner well known inthe art. The mixing of the water and expanded vermiculite is effected by grinding the vermiculite and water mixture until the ver- 35 miculite is in an extremely finely divided state producing a suspension of vermiculite in water and having about the consistency of house paint. This condition may be obtained by ball milling the water vermiculite mixture for about 20 to 24,
40 hours, the vermiculite initially being capable of passing through a 60 mesh screen. The particles of vermiculite after mixing in the ball mill are in the form of small leaves or fiat crystals.
The water-vermiculite mixture thus prepared 45 is in effect a paint in which water is the vehicle instead of oil. It may be applied to sheet steel by means of a brush, spray, or rubber rolls and then dried in an oven at a temperature suinciently high to evaporate the water. The coated 50 sheets may be annealed in the usual manner, i. e.,
in a pack in a furnace having a roof temperature of about 875 C. and an atmosphere of air or neutral gas. The water vermiculite coating applied to silicon steel laminations as heretofore 55 pointed out provides a high degree of insulation between successive laminations andappears to give a relatively small reduction in total watt loss, i. e., up to about 2.5% as compared with laminated sheets having a core plate enamel coating. This reduction in watt loss is possibly due to the fact-that the coating prevents excessive oxidation of the sheet steel. Furthermore, the coating prevents sticking together of the steel sheets during the annealing process. The vermiculite forms a very tight coating which cannot be rubbed off the steel or removed any easier than the regular anneal scale and gives a surface insulation resistance which is greater in both air and hot oil than that which can be obtained with core plate enamel heretofore employed in transformer construction.
The vermiculite insulation forms a very thin film coating and causes no appreciable increase in the space factor permissible in transformer construction. The vermiculite, during the annealing process, apparently combines with the natural scale formation on the steel thereby providing a highly insulating coat. vermiculite, however, even without the assistance of the steel scale is a particularly efilcient insulator due to its leafing action.
While I prefer to employ a mixture of about 20 parts vermiculite and about 100 parts of water, these quantities are not critical and may be varied widely. Also, instead of employing water, I may mix the vermiculite with Water solutions which may be beneficial to the steel. Although I prefer to employ a mixture of vermiculite and water, I may employ instead of the vermiculite other materials having approximately the same chemical analysis or crystallographic form.
What I claim as new. and desire to secure by Letters Patent of the United States, is:
l. The method of electrically insulating sheet steel which comprises applying to the steel a film consisting of a mixture of water and expanded vermiculite, drying the mixture to evaporatethe water and baking the vermiculite onto the steel during an anneal.
2. In the'manfacture of magnetic sheet steel, 5 the process which comprises coating said steel sheets prior to annealing with an electrically insulating film consisting of a water-vermiculite mixture.
3. Sheet steel suitable for use as a transformer lamination and having an insulating coating thereon, said coating consisting substantially of a vermiculite film baked onto said sheet steel.
Silicon steel sheets suitable for use in transformer laminations, said sheets having an electrically insulating film thereon, said film consisting substantially of vermiculite baked thereon.
5. Annealed silicon steel having a coating thereon, said coating consisting of vermiculite bonded to the natural scale formation of the steel.
6. Annealed silicon steel having a coating thereon, said coating consisting of vermiculite bonded to the natural scale formation of the steel, said coating being free from alkaline bonding ma- 10 terial.
7. Siliconsteel having a thin, tight, insulating coating thereon, said coating consisting substantially of vermiculitebonded to said steel and having the property of preventing sticking and excessive oxidation during anneal and causing no appreciable increase in the space factor when the coated steel is employed as laminations in transformer cores.
WESTON MQRRILL. 10
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US79941A US2215295A (en) | 1936-05-15 | 1936-05-15 | Surface insulation for magnetic sheet steel |
DEA82923D DE706944C (en) | 1936-05-15 | 1937-05-12 | Insulating material, especially for magnetic sheets |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US79941A US2215295A (en) | 1936-05-15 | 1936-05-15 | Surface insulation for magnetic sheet steel |
Publications (1)
Publication Number | Publication Date |
---|---|
US2215295A true US2215295A (en) | 1940-09-17 |
Family
ID=22153798
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US79941A Expired - Lifetime US2215295A (en) | 1936-05-15 | 1936-05-15 | Surface insulation for magnetic sheet steel |
Country Status (2)
Country | Link |
---|---|
US (1) | US2215295A (en) |
DE (1) | DE706944C (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2426445A (en) * | 1943-07-07 | 1947-08-26 | Gen Electric | Insulation for magnetic steel and the like |
US2457515A (en) * | 1941-11-13 | 1948-12-28 | Bell Telephone Labor Inc | Insulating coating compositions and method of making |
US2558411A (en) * | 1945-05-22 | 1951-06-26 | Battelle Development Corp | Ceramic coating composition, coated article, and method of making same |
US2704978A (en) * | 1953-03-12 | 1955-03-29 | Du Pont | Electrically fired gas expansion blasting device |
US2906649A (en) * | 1955-04-07 | 1959-09-29 | Siemens Ag | Heat-resistant electric insulation and method of manufacture |
US3001571A (en) * | 1957-08-05 | 1961-09-26 | Minnesota Mining & Mfg | Synthetic mica flakes and structures |
US3274019A (en) * | 1964-11-06 | 1966-09-20 | Alton V Oberholtzer | Impregnation and coating with splitoffs of vermiculite and products thereof |
-
1936
- 1936-05-15 US US79941A patent/US2215295A/en not_active Expired - Lifetime
-
1937
- 1937-05-12 DE DEA82923D patent/DE706944C/en not_active Expired
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2457515A (en) * | 1941-11-13 | 1948-12-28 | Bell Telephone Labor Inc | Insulating coating compositions and method of making |
US2426445A (en) * | 1943-07-07 | 1947-08-26 | Gen Electric | Insulation for magnetic steel and the like |
US2558411A (en) * | 1945-05-22 | 1951-06-26 | Battelle Development Corp | Ceramic coating composition, coated article, and method of making same |
US2704978A (en) * | 1953-03-12 | 1955-03-29 | Du Pont | Electrically fired gas expansion blasting device |
US2906649A (en) * | 1955-04-07 | 1959-09-29 | Siemens Ag | Heat-resistant electric insulation and method of manufacture |
US3001571A (en) * | 1957-08-05 | 1961-09-26 | Minnesota Mining & Mfg | Synthetic mica flakes and structures |
US3274019A (en) * | 1964-11-06 | 1966-09-20 | Alton V Oberholtzer | Impregnation and coating with splitoffs of vermiculite and products thereof |
Also Published As
Publication number | Publication date |
---|---|
DE706944C (en) | 1941-06-10 |
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