US2476049A - Lifting magnet - Google Patents

Description

' July l2, 1949.

J. D. LEITCH LIFTING MAGNET Filed'July 15, 1945 5 Sheets-Sheet 2 ,Y////////// ffl 1N VEN TOR.

BYJOHN 0. l ,5/ TcH l Zio( my. M

AT1-ORNE K5 July 12, 1949. J. D. ElTcH 2,476,049

LIFTING MAGNET NVENTOR.

a/oH/v D. E/TcH /4-7 ro fiM/E V5 Patenfed July 12, 1949 2,476,049

Company, Clev'el'and, Oh'io; a" corporation" of OhfU" vantig'e" .0f WODIdl Il@ fili' replacementVY of the bottom of the container. The outer marginal portion of the flange is fastened to the outer pole piece of the magnet frame by a continuous annular weld and the inner bottom edge portion of the container is fastened to the inner pole piece by a continuous annular weld. The provision of the peripheral flange permits the outer side wall portion of the coil container to be made of thin sheet metal welded to the top and bottom members of the container since the large weld provided to secure the coil container to the magnet frame is spaced from the side wall by the width of the flange and thus the heat therefrom does not adversely affect the side wall portion or the welded connection between the side wall portion and the bottom of the container. Since all of the welds are annular and coaxial with the frame, to remove the coil from the annular groove or channel in the frame, it is only necessary to machine out annular welds, which can be done by machine tools that are generally available and by a single centering of the magnet in the machine. The winding in a preferred embodiment is prevented from rotating relative to the enclosure by the combined action of frictional forces between the winding and the top and bottom walls of the enclosure and by adhesive properties of insulating material within the container.

It is an object of this invention to provide an improved lifting magnet of the circular type.

Another object is to provide a lifting magnet having the foregoing advantages, and in which the foregoing disadvantages are eliminated.

Still another object is to provide an improved winding construction for a circular lifting magnet.

Further objects are to provide an improved lifting magnet of the circular type having a hermetically sealed coil unit separate from the magnet frame, torprovide a lifting magnet having a hermetically sealed coil enclosure welded to the magnet frame, to provide a hermetically sealed coil enclosure for a circular lifting magnet having an external peripheral fiange portion for use in welding the enclosure to the magnet frame, to provide an improved terminal box construction for a lifting magnet, to provide improved means for preventing rotation of -a winding insulated from and sealed within a metallic enclosure, and to provide an improved terminal lead construction for a lifting magnet.

Other objects and advantages will become apparent from the following description wherein reference is made to the drawings, in which Fig. 1 is a top plan view of the magnet;

Fig. 2 is an enlarged diametrcal sectional view taken generally along the line 2 2 of Fig. 1;

Fig. 3 is a relatively enlarged fragmentary top plan view of a portion of the coil assembly;

Figs. 4 and 5 are sectional views taken generally along lines 4 4 and 5 5, respectively, of Fig. 3;

Fig. 6 is a fragmentary diametrcal sectional view taken generally as indicated at 6 6 in Fig. 1;

Fig. 7 is a fragmentary diametrcal sectional view of a portion of a modified magnet, and

Fig. 8 is a fragmentary sectional view taken generally along line 8 8 of Fig. '7 with parts omitted.

Referring principally to Fig. 2, the lifting magnet illustrated in the drawings comprises a circular magnetic frame Hl having integral therewith a cylindrical inner pole piece Il and an annular outer pole piece I2. The pole pieces il and l2 form downwardly projecting concentric exte ions of the frame l and define an annular winding space i4 therebetween which is open at the bottom to receive an annular coil unit to be described. The inner pole piece ll is in the form of a hollow cylinder with an axial opening I6 extending through the magnet frame which opening has a lower frusto-conical portion Ilia and an upper cylindrical portion lb. A unitary inner or central pole shoe i8 has an upper integral portion Ia complementary to and tting snugly in intimate flux conducting relation with the surfaces of the opening IG and a lower fiange-like portion lb provided with an annular shouldered recess 80 for receiving an inner marginal portion of an annular non-magnetic protective plate 2l preferably formed of cast manganese steel. The pole shoe I3 has the usual axial opening I9 therethrough and is secured in position by a means located entirely at the top of the magnet frame i3 and preferably by a continuous annular welded connection 22 formed at the outer marginal portion of the top surface of the pole shoe.

The outer marginal portion of the plate 2l is received in an annular shouldered recess 24a of an annular outer pole shoe 24 having an upwardly extending annular flange Zlib around its outer periphery which fits into an annular shouldered recess I2a cut in the outer periphery of the outer pole piece I2 adjacent its lower face. A continuous welded connection 25 may be made between the pole shoe 24 and the pole piece l2 along the top of the flange 24h to secure the pole shoe 24 in position. This welded connection 25 is annular and coaxial with the pole piece.

Because manganese steel is difficult to machine, provision has been made for reducing to a minimum the amount of finishing required on the plate 2l. To this end, concentric downwardly extending annular projections or ridge portions 2 la and 2 lb are formed on the plate 2l and have their lower face surfaces finished and in engagement with the outer marginal portions of horizontal finished surfaces 18d and 24e of the recesses itc and 24a, respectively. With the exception of the finished areas of the ridges 21a and 2lb, the lower face surface of the plate 2| may be left unfinished. The plate 2| is preferably of hollowed ribbed construction, as suggested in Fig. 2, to provide greater strength and rigidity for unit weight and to insure a sound casting. Clearance 26 is provided at the top of the ribs so that finishing of the entire top surface of the plate 2l is not necessary. In order to further reduce the amount of finishing required on the top surface of the plate 2|, the inner and outer marginal portions thereof are provided with a plurality of circumferentially spaced raised areas or pads 2 lc which have their top surfaces 2 Id finished thereby to provide concentric interrupted annular bearing areas for the coil unit, the surfaces 2|e between the pads being left unfinished.

Hoisting chains 23 are secured respectively as by pins 23a to a plurality of circumferentially spaced lugs 21 formed on the top of the frame I0. The lugs 2l extend to the outer peripheral edge of the frame and have respective openings 21a therein for receiving cables or the like (not shown) for the purpose of exerting sidewise forces on the magnet when necessary.

So long as an annular winding space IB is provided, the specific arrangement of the pole shoes, protective plate, and the magnet frame is immaterial to the present invention; the construction described for illustrative purposes is similar to that described and claimed in a copending patent application of D. C. Wright and A. L. Ward,

hermetically sealed, those having adhesive properties may be used herein instead of the material above described.

The coil unit is received in the annular channel IIS with the bushings 58 fitting into respective circumferentially spaced recesses |2b (Fig. 2) formed on the outer pole piece l2. The annular welded connection 3|) between the weld 3|, the hub 28, and the inner pole piece secures the coil unit to the inner pole piece and a continuous annular welded connection 6| formed at the outer peripheral edge 29h of the plate 29 within a shouldered recess adjacent the lower face of the pole piece l2 secures the coil unit to the outer pole piece |2. Since the weld 6| is spaced from the side Wall 5| by the width of the flange 29e, a larger and stronger weld can be made Without risk of deforming, overheating, or otherwise damaging the thin sheet metal of the wall 5| and the welded connection 55 when making the weld 6|.

The leads d5 and 46 extend in circumferential spaced relation through an opening E2 in the frame It) extending from the top of the annular recess lli and enter a terminal box 64 formed on the top of the frame. A tube or sleeve 62' pressed into the opening 62 rests upon the insulator i9 and the hub 28. The annular joint around the bottom of the sleeve G2 is sealed from the inside of the sleeve by impregnated asbestos cord (not shown), and then the sleeve 62' is preferably filled with the material Gil which is allowed to polymerize without externally applied heat.

The terminal box 64 (Figs. 1 and 2) has end walls 84a and 64b, side walls 64e and 54d, and a central wall 64e dening two chambers 65 and '66. The upper end portions of the leads 45 and 11S are secured to respective circumferentially spaced terminal studs 68 which are received in respective spaced openings in the wall 64e, each of the studs 6B being insulated from the wall 64e by a sleeve l2 and a spacer or collar i4. Suitable gaskets 1 3 are provided to make a hermetic seal around the studs S8. Circumferentially spaced openings i5 closed by respective pipe plugs 'i6 are provided in the wall 64a to permit drilling of the openings in the wall 64e and manipulation of the magnet connections. A top wall 64j of the terminal box 64 has a pair of threaded openings which are closed by plugs 'I8 and 19, respectively.

Leads 8G and 8| (Fig. 1) of a cable 82 are secured to the respective terminal studs 68 within the chamber 65 and pass through a suitable seal (not shown) in the side wall Md. The cable 82 is protected from mechanical abuse by a wall 85 extending outwardly from the wall 615e and having a portion extending in parallel spaced relation to the wall 64d until it merges into one of the lugs 21. A lead clamp 3% is provided to secure the cable 82 in position.

The modification of Figs. 7 and 8 provides means in addition to the adhesive and frictional forces of the principal embodiment for holding the winding against relative rotation with respect to its enclosure. in Figs. 7 and 8, pairs of vertically aligned and spaced U-shaped brackets Bil are secured, as by spot-welding, to the inner surface of the wall member 5| at circumferentially spaced positions (only one pair being shown). Opposite the pairs of brackets 953, the insulation plates 35a to 35e, inclusive, are provided with respective notches 9| for receiving an elongated locking member S32 formed of insulating material.

An alternative method of winding the coil sections 32a, B2b, 32e. and 32d is to be preferred when the locking members 92 are used. In the alternative method, the hub 28 and the plate 4| secured together by the Welded connection Ml constitute the spider upon which the coil sections are wound. After the coil winding operation, the members 92 are slipped into position in the recesses 9| and then the bottom plate 29 is secured to the hub 28 by the welded connection 3|. The wall member 5l is then secured to the plate 29 at one point and then progressively bent to cylindrical configuration and welded in place by the welded connection 55. A welded connection 94 (Fig. '7) is formed between the top edge of the wall member 5| and the outer peripheral edge or the plate 4|. It will be noted that before the welded connection 94 is made, the coil sections can be compressed and that since the upper portion of the wall members 5| overlaps the outer edge of the plate 4|, the vertical dimension of the plate 5| is not critical.

Thus the coils not only are hermetically sealed but also are fixed in position circumferentially relative to the magnet frame. This is accomplished (a) by securing the coils in fixed position in the hermetically sealed container either by a combination of frictional forces due to the axial compressive stresses on the coils with the adhesive forces due to the insulating material which is thermal setting and bonded to the coils and to the walls of the container or with mechanical interlocking of the coil insulation discs with the insulation strips interlocked, in turn, with the container walls, and (b) by Isecuring the container, in turn, to the magnet frame by continuous annular welds coaxial with the frame. Since all of the welds are annular and coaxial, all can be removed easily for servicing or disassembling the magnet by centering of the magnet frame in a suitable rotary cutting machine and machining ofi the weld.

I claim:

1. A lifting magnet comprising a magnetic frame member having concentrically arranged inner and outer pole pieces extending downwardly therefrom and dening an annular winding space therebetween, an annular, hermeticallysealed, coil-containing enclosure received in said winding space, said enclosure comprising a relatively thick metal bottom wall portion and an outer cylindrical metal side wall portion, said bottom wall portion and said side wall portion being welded together, and said bottom wall portion having an integral marginal portion extending outwardly from said side wall portion to define a ilange, and a Welded connection between the outer peripheral portion of said ilange and said outer pole piece.

2. A.' lifting magnet comprising a magnetic frame member having concentrically arranged inner and outer pole pieces extending downwardly therefrom and dening an annular winding space therebetween, an annular, hermetic-allysealed, coil-containing enclosure received in said winding space, said enclosure comprising a relatively thick metal bottom wall portion and an outer cylindrical metal side wall portion of less thickness than the bottom Wall portion, said bottom wall portion and said side wall portion being welded together, and said bottom wall portion having an integral marginal portion extending outwardly from said side wall portion and transversely with respect to the axis of said pole pieces to define a ilange, and a welded connection between the outer peripheral portion of said flange and said outer pole piece.

3'. ,a lifting magnet comprising a magnetic frame member having ,coil-centinela arranged inner and einer noie nieces ,extending down ardly therefrom and .donnine annular ding Space therebetween an emision bermen allysealedl Gailreontainine .enclosure received vin said Winding space, saisi .enclosure ,comprising .a relatively thick metal bottom wall portion and an outer cylindrical sidewall portion formed of relatively thin sheet metal, a continuous annular welded connection between said `wall portions securing said'wall portions together with an integral marginal portion of said bottom wall portion extending outwardly from said side wall to dene a flange, and a Welded connection between the outer marginal portion of said flange and the inner marginal portion of said outer pole piece, whereby said last named welded connection can be made without effect on said rst named welded connection or on said sidc wall portion.

4. An annular, hermetically-sealed coil unit for reception into an annular groove in the lower face of a circular lifting magnet frame, comprising an annular metal container having a tubular hub portion and an outer cylindrical side Wall portion joined by planular top and bottom members, a winding wound upon said hub portion between said top and bottom members, said winding when uncompressed being of greater thickness than the normal distance between said top and bottom members and being held in compressed condition by and between said top and bottom members thereby to cause frictional forces which oppose relative rotation between portions of said Winding and between said winding and said container.

5. An annular hermetically-sealed coil unit for reception into an annular groove in the lower face of a circular lifting magnet frame, comprising an annular metal container having a tubular hub portion and an outer annular side wall portion joined by planular top and bottom wall members, a winding wound upon said hub portion between said top and bottom members, said winding when uncompressed being of greater thickness than the normal distance between said top and bottom members and being `compressed by said top and bottom members thereby to cause frictional forces which oppose relative rotation between said winding and said container, said winding further being of lesser diameter than the inside diameter of said side wall portion thereby to dene an annular space within and at the outer marginal portion of said container, and insulating material within said space and having the property of adhering to said winding and to said walls thereby opposing relative rotation between said container and said winding.

6. In a circular lifting magnet frame having a top surface sloping downwardly and outwardly from the axis of the magnet, a terminal box comprising a closed chamber dened by four side walls cast integral with said frame and a portion of the frame forming the bottom wall, one of said side walls of said box extending in the direction of said slope and having an opening for magnet leads, an integral wall extending laterally outwardly from said one side wall and positioned further from the axis than said lead opening, a suspension lug on said magnet frame, said outwardly extending wall having a portion extending generally alongside and spaced from said one wall and merging at its inner end with said lug thereby to provide a protective barrier for and exteriorly of said opening.

7. A lifting magnet comprising a frame having l0 concentrically arranged inner and outer pole pieces extending 'downwarf n Atherefrom and vderining a winding space therbetwnl'a'n opening between said space and the tp'f'said'frameQa Cylindrical het resister Syrioiireins Said inner pole piece, an axially directed groove in said hub member V.facing said winding space, a multi-layered winding on said hub member, a terminal lead vreceived in said groove and extending from the lowermprst layer of said winding through said opening, and an elongated C-shaped insulator received insaid groove and partially enclosing said lead.

8. In a lifting magnet, a frame having an annular groove in the lower face, an annular, hermetically-sealed coil unit for reception in said groove and comprising an annular container having an inner cylindrical hub portion, an outer cylindrical side wall portion, and a winding wound upon said hub portion and of lesser diamcter than the inside diameter of said side wall portion thereby to denne an annular space Within said container, and circumferentially spaced means in said space and mechanically interloclred with the winding and lwith said side wall portion :For opposing relative rotation of the winding and side wall portion.

9. In a lifting magnet, a frame having an nular groove in the lower face, an annular, liermetically-sealed coil unit for reception in said groove and comprising an annular container havF ing an inner cylindrical hub portion, an outer cylindrical side wall portion, and a winding wound upon said hub portion and of lesser diamcter than the inside diameter of said side wall portion thereby to define an annular space with-- in said container, said winding comprising a plu-- rality of axially spaced coils and insulating discs therebetween and interlocked with the adjacent coils, and said discs being of greater diameter than the coils and extending into said annular space, and circumferentially spaced means inW terlocking said discs and said side wall portion for opposing relative rotation of said coils and side wall portion.

1G. In a lifting magnet, an annular, hermetically-sealed coil unit, a magnet frame having an annular groove in the lower face accornrnodati1 ng said unit, said unit comprising an annular metal container having a tubular hub portion and outer annular side wall portion joined by planular top and bottom wall members, a winding Wound upon said hub portion between said top and bottom members, said winding when uncompressed being of greater thickness than the nor-- mal distance between said top and bottom members and being compressed by said top and bottom members thereby to cause frictional forces which oppose relative rotation between said winding and said container, said Winding lurther being of lesser diameter than the inside diameter of said side Wall portion, thereby to define an annular space Within and at the outer marginal portion of said container, insulating material within said space adhering to said windu ing and to said walls and thereby opposing relative rotation between said container and said winding, and means anchoring the container to the frame for opposing relative rotation of the container and the frame about the axis of the groove.

JOHN D. LEITCH.

(References on following page) l1 REFERENCES CITED Nlmllg The following referenloes are of record in the 133152530 file of this patent: 1,813,976

UNITED STATES PATENTS 5 glll Number Nam'e Date 3791664 844,578 Cavanagh Feb. 19, 1907 1,015,728 Eastwood Jan. 23, 1912 1,326,366 Milton Dec. 3o, 1919 10 Number 1,334,504 Parker Mar. 23, 1920 135,265 1,455,199 Groten May 15, 1923 Na-me Date Myers July 3, 1928 Kurath July 28, 1931 Goff Aug. 18, 1931 Hodgson Oct. 12, 1937 Miles May 3, 1938 Stanko July 3, 1945 FOREIGN PATENTS Country Date Great Britain Sept. 7, 1922

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