US2946973A - Magnetic core box - Google Patents

Magnetic core box Download PDF

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Publication number
US2946973A
US2946973A US800019A US80001959A US2946973A US 2946973 A US2946973 A US 2946973A US 800019 A US800019 A US 800019A US 80001959 A US80001959 A US 80001959A US 2946973 A US2946973 A US 2946973A
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Prior art keywords
container
lid
edges
core
inch
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Expired - Lifetime
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US800019A
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Carroll W Lufcy
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Dynacor Inc
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Dynacor Inc
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Priority to US800019A priority Critical patent/US2946973A/en
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00Details of transformers or inductances, in general
    • H01F27/24Magnetic cores
    • H01F27/25Magnetic cores made from strips or ribbons

Description

July 26, 1960 c. w. LUFCY MAGNETIC CORE BOX.
Filed March 17, 1 959 INVENTOR Carroll WLzLfg/ ATTORNEYS United States Patent MAGNETIC CORE B'ox Carroll W. Lufcy, Silver Spring, Md., assignor to Dynacor Inc., Kensington, Md., a corporation of Maryland Filed Mar. 17, 1959, Ser. No. 800,019
8 Claims. (Cl. 336-213) This invention relates to a box or container for a magnetic core, and more particularly to a container for a tape-wound magnetic core.
This application is a continuation-in-part of prior application Serial No. 595,980, filed July 5, 1956 and now abandoned.
Currently, tape-wound magnetic cores are widely used in various electrical and electronic applications, such as -magnetic amplifiers, magnetic memories for computors,
etc. In these applications, it is highly important that the core container or box satisfies a number of stringent requirements.
Primarily, the container must be rigid to preserve and protect the magnetic characteristics of the tape-wound core which is highly strain sensitive. Since these containers are frequently immersed or potted in various oils and compounds, they must be sealed against inward seepage of these compounds. Furthermore, a cross-sectional configuration which uniformly spaces a wound coil about the magnetic core within the box with a minimum distance between a coil and the core is desirable. In addition, to facilitate application and preservation of the wind ings as well as providing a neat and attractive appearance, the external surface of the container should be substantially smooth. Still further, the container must not provide a complete conductive circuit about the winding. A practical container must fulfill these stringent requirements with a structure which is simple and economical to manufacture. None of the boxes or containers heretofore proposed have provided a structure which satisfies all of these aforementioned demands.
An object of this invention is to provide a container for a magnetic tape-wound core having a simple structure well adapted for economical fabrication which simultaneously fulfills all of the aforementioned requirements for a commercially acceptable enclosed tape-wound magnetic core.
In accordance with this invention, an enclosed magnetic tape-wound core includes a toroidal wound core of magnetic tape disposed within a thin-walled hollow anodizable metal toroidal container having an open side. A suitable cushioning material separates the core from adjacent surfaces of the container and the lid which closes the open side of the container. This lid is also made of anodizable metal, and both the lid and the container are anodized before assembly to insure that their adjacent surfaces are insulated from each other to break any closed circuits about the core which might be formed by these conductive metal elements. Both inner circumferential edges of the container are internally recessed to provide shoulders for supporting the lid, and both circumferential edges of the outer surface of the lid are also recessed to interlock within the edges of the container when they are deformed to lock over the lid and seal the open end of the container. A thin sheet of material having a slick non-wetting surface, such as Teflon, is disposed between the container and lid before it is sealed 2,946,973 Patented July 26, 1960 to form a liquid-tight joint between the lid and container when merely enough pressure to form a visually smooth joint is applied to interlock the edges of the container with the lid. This slight pressure is suiiicient to satisfactorily seal the joint between the container and lid against liquid seepage without applying enough force to adjacent portions of the container, sheet or lid to break through the insulation provided by the anodized coating and sheet.
Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which:
Fig. l is a perspective view of an embodiment of this invention in completed form;
Fig. 2 is a view in elevation partially broken away to illustrate a cross section of an embodiment of this invention; and
Fig. 3 is a portion of a cross-sectional view in elevation of a portion of another embodiment of this invention.
In Fig. l, a finished and assembled enclosed magnetic core 10 is shown to illustrate the neat and attractive, as 'well as functional, structure of a core 10 made in accordance with this invention. This core 10 includes a metal container 12 and a lid 14. Various features of this invention, later described in detail, cooperate to provide its highly functional and attractive structure. All surfaces of this core join smoothly and continuously to facilitate the application and preservation of windings or coils. All corners are, accordingly, rounded which greatly facilitates coil winding and prevents snagging or tearing of the coils after they are wound. The container 12 is made, for example, of aluminum to provide necessary rigidity without introducing unnecessary bulk. Aluminum is light, machineable and ductile, yet fairly strong. The lid 14 is also made, for example, of aluminum, and these containers may be provided in a variety of sizes, ranging from small to large, including boxes having fractional inch diameters and those several inches in diameter. ranging up to six inches in outside diameter and up to one inch high, the wall and lid thicknesses of representative aluminum boxes range, for example, from 0.020 inch to 0.050 inch.
As shown in Fig. 2, core 10a includes an open-sided hollow toroidal or doughnut-shaped container 12:: fabricated of aluminum, for example. A tape winding 16a of typical construction is placed within the cavity 18a provided within the metal container 12a. Tape winding 16a is surrounded by a body of cushioning material 20a which may be, for example, an unvulcanized rubber not including a vulcanizing agent. A silicone material, such as nvulcanized Silastic, may be used to advantage. The winding and cushioning substance are maintained below the shoulders 22a provided by the internally recessed edges 23a and 24a of the container. Edge 23a is shown before it is deformed to seal the container, and edge 24a is shown in the sealed condition. A gasket 26a is interposed between the lid 14a and the edges and contents of the container. The clearance between the annular lid 14:: and the edges of the container are selected to permit the gasket to be interlocked between the lid and container walls. Both circumferential edges 280 on one side of the lid 14a are notched or recessed to provide a space for receiving the deformed edges 23a and 24a of the container 12a and the gasket 26a. When the edges 23a and Z Z-a are rolled inwardly to lie within the recesses 28a in the lid 14a, the gasket 26a accordingly forms a tortuous path between the interlocked edges of the body and the lid. The outer surface of the container is maintained smooth by virtue of the interlocking of the edges of the body For boxes within the recesses in the lid. I Any protruding portions of the gasket 26a are cut off clean with the exterior of the container surface to preserve the smooth exterior of the surface.
Gasket 26a is made, for example, of a thinsheeti'of slick non-Wettingrnaterial which provides a liquid-tight joint between the interlocked edgesof the container and lid even though they are only deformed together by'a force which is just sufiicient to provide a visually sealed joint which is pleasing to the eye. A particularly advantageous material for this gasket is a thin sheet of Teflon, a tetrafluoroethylene polymer made by the DuPont Company of Wilmington, Delaware, which, for example, ranges in thickness from 0.002 inch to 0.006 inch. This gasket, accordingly, advantageously utilizes a sheet-of this material which has a nominal thickness of 0.004 inch. A sheet of this material provides exceptional sealing characteristics and prevents liquid seepage through the joint formed between the deformed edges of the container and the lid even though the pressure exerted upon it by the deformed edges is extremely slight. Furthermore, the insulating properties of Teflon, in conjunction with the anodized surfaces of the adjacent parts of the lid and container prevent the completion of a deleterious electrical circuit about the core through the lid and container. This remarkable characteristic of this sheet of slick .ma terial insures the maintenance of insulation between a lid and container made of a conductive material, such as aluminum, even though Teflon alone in a thin sheet might be too fragile, and anodizing alone would not dependably insulate if greatersealing pressures than the remarkably slight ones described herein had to be utilized. The joint provided in accordance with this invention unexpectedly provides adequate enough insulation and sealing characteristics to effectively prevent short circuits and the entrance of liquids, such as potting compounds, into the container. Although the exact reason for the sealing phenomenon is not fully understood, it is believed that the slick non-wetting surface of Teflon prevents capillary action from drawing a liquid through the joint into the container even though crevasses of substantial magnitude might exist. 7
Another embodiment 10b of this invention is shown in the cross-sectional view illustrated in Fig. 3 which also, for example, shows materials identical to those used in Fig. 2. In Fig. 3, however, the edges 28b of the lid 14b are recessed by being chamfered instead of beingnotched. Recessed edges 24b of the container 12b accordinglylie over and interlock with chamfered edges 28b of the lid 14b to form a'smooth continuation of container 12]) when its edges 24b are deformed."
What is claimed is:
'1. An enclosed magnetic tape-wound core comprising a toroidal wound core of magnetic tape, a thin-walled hollow toroidal container made of an anodizable metal 4 having an open side, said core being inserted within sai container, an annular lid also made of an anodizable metal, said lid being substantially rigid in its planar direction and including recessed circumferential edges upon its outer surface, the inner and outer edges of said circumferential container being internally recessed to provide shoulders constructed and arranged to support said lid in a position to have its'outer surface form a substantially smooth continuation of the outside wall of said container when said edges of said container are deformed to lie within and'to" interlock with said recessed edges of said lid, said lid being disposed against said shoulders and having its recessed edges interlocked within said deformed circumferntial edges of said container to provide a joint of substantial lengththerehetween, a cushioning material disposed within said container separating said core from the adjacent surfaces of said container and lid, the dimensions of said container and lid and the thickness of'said cushioning material disposed'betwe'en said adjacent surfaces being constructed and arranged to pro vide a substantially uniform perpendicular dimension from the outer surfaces of said core to respective closest outer surfaces of said container and lid, the'surface of said container and lid being anodized to provide insulation between said lid and said container, and a thin sheet of insulating material having a slick non-wetting surface being interposed between said lid and said container and interlocked within said joint between said deformed circumferential edges'of said container and said recessed edegs of said lid to provide an effective liquid-tight'seal and insulation between said lid and container when only enough force is appliedto deform said circumferential edges sufliciently to provide a visually smooth joint.
2. An enclosed magnetic tape-wound core as set forth in claim 1 wherein said sheet is comprised of Teflon.
3. An enclosed magnetic tape-wound core as set forth in claim 2 wherein said sheet of Teflon ranges in thickness from 0.002 inch to 0.006 inch.
4. An enclosed magnetic tape-wound core as set forth in claim 3 wherein said sheet of Teflon is 0.004 inch thick.
5. An enclosed magnetic tape-wound core as set forth in claim 3 wherein the wall thickness of said container and said lid ranges from 0.020 inch to 0.050 inch.
6. An enclosed magnetic tape-wound core as setforth in claim 1 wherein said edges of said lid are sharply notched. v e
'7. An enclosed magnetic tape-wound core .as set forth in claim lwherein said edges of said lid are chamfered.
8. An enclosed magnetic core as set forth in claim l wherein said container and said lid are made of aluminum.
References Cited in the file of this patent Special Magnetic Alloys and Applications, pp.. 843- 845, Electrical Engineering, September 1948.
US800019A 1959-03-17 1959-03-17 Magnetic core box Expired - Lifetime US2946973A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3130355A (en) * 1961-05-03 1964-04-21 Warner Electric Brake & Clkutc Electromagnet
US3179908A (en) * 1960-08-25 1965-04-20 Emp Electronics Inc Heat exchange means for electromagnetic devices
US3183463A (en) * 1962-07-20 1965-05-11 Westinghouse Electric Corp Low sound level electrical transformer
US3183413A (en) * 1962-12-12 1965-05-11 Westinghouse Electric Corp Protective means for superconducting solenoids
US3215905A (en) * 1963-12-16 1965-11-02 Otto N Bloom Three piece bobbin of dielectric material for electric coils
US4603314A (en) * 1982-10-26 1986-07-29 Tdk Corporation Inductor
US20070031298A1 (en) * 2001-06-07 2007-02-08 Pende, Inc. Aromatic substance heating device

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3179908A (en) * 1960-08-25 1965-04-20 Emp Electronics Inc Heat exchange means for electromagnetic devices
US3130355A (en) * 1961-05-03 1964-04-21 Warner Electric Brake & Clkutc Electromagnet
US3183463A (en) * 1962-07-20 1965-05-11 Westinghouse Electric Corp Low sound level electrical transformer
US3183413A (en) * 1962-12-12 1965-05-11 Westinghouse Electric Corp Protective means for superconducting solenoids
US3215905A (en) * 1963-12-16 1965-11-02 Otto N Bloom Three piece bobbin of dielectric material for electric coils
US4603314A (en) * 1982-10-26 1986-07-29 Tdk Corporation Inductor
US20070031298A1 (en) * 2001-06-07 2007-02-08 Pende, Inc. Aromatic substance heating device

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