US979750A - Lifting-magnet. - Google Patents

Description

A. G. EASTWOOD.

LIFTING MAGNET.

APPLICATION FILED mun, 1908.

Patented Dec.27, 1910.

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LIFTING MAGNET.

APPLICATION FILED JULY17,1908.

Patented Dec. 27, 1910..

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A. 0. EASTWOOD.

LIFTI'NG MAGNET.

APPLICATION FILED JULY 17, 1908.

A Patented Dec, 27, 1910.

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ATTORNEY ARTHUR C. EASTWOOD, 0F CLEVELAND, OHIO.

LIFTING-MAGNET.

Specification of Letters Patent.

Patented Dec. 27, 1910.

Application filed July 17, 1908. Serial 443,974.

To all whom it may concern:

Be it known that I, ARTHUR 0. EAST- wooo, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented or discovered new and useful In'iprovements in Lifting-Magnets, of which the following is a specification.

My invention relates to an improved form of lifting magnet and particularly to that class of liftingmagnets adapted to lifting iron or steel products, such as pig iron from an indiscrin'iinate pile. It has been demonstrated that a lifting magnet which will lift ten tons in the form of a relatively smooth homogeneous piece of steel, such as an ingot or a bloonnmay not lift a single pig of iron weighing 100 pounds from an indiscriminate pile of pigs. This, of course, shows that there must be essential dill'erenccs between a lifting magnet for handling pig iron and other miscellaneous products of iron and steel and a lifting magnet for holding homogeneous material such as plates, blooms, billets, ingots, etc. In fact: up to within iive years ago it was considered connnercially impossible to handle miscellaneous magnetic material, such as pig iron with a lifting magnet, although lifting magnets for ham dling plates, blooms, etc. have been in commercially successful operation for more than fifteen years in the past, as far as l'lHIOW, all COUlll'lClCittllV successful lilting magnets for handling pig iron and similar bulk magnetic innit-rial have been of annular ,l'orni. Such a lifting magnet is illustrated and described in llnited States Patent, No.79l-,0t5t3 issued to me July 41'. 1903.

The form of lifting magnet with which this a 'iplication is concerned possesses the following advantages: 1st. The initial reluctance of the magnetic circuit of the lifting magnet without its load is high, thus adapting it to the liamll'ing of material of high reluctance, sucl as pig iron. 2nd. The air gap between the poles is large and the surface of the poles cxposml to leakage from pole to pole is very small, thus reducing the amount of magnetic latkage and increasing the eiliciencv of the magnet. 3rd. The coil or magnetizing winding is of small depth compared with its length thus permitting of a minimum weight of conductor in the winding and also providing for the rapid dissipation of the heat generated within the winding. 4th. The poles of the magnet are symn'ietrically arranged with respect to the magnetizing winding and are normally of the same lilting power. 5th. The larger part of the impact due to lowering the magnet upon the load to be lifted comes upon the polar faces, thus relieving the magnetizing winding from the effects of such impact. (3th. The form of the magnet is such that looth poles almost invariably come into contact with the surface of an irregular pile. 7th. The magnet is of light weight for a given lifting capacity.

In general terms, my improved magnet has a horizontal core of considerable length conniared with its diameter. The magnetizing winding has its axishorizontal andsurrounds the core and pole pieces depend from either end of the core.

In an annular form oi magnet, it will be understood that the leakage between the core and the outer pole varies directly with the area of the cylindrical outer surface of the core and theinner surface of the outer pole and varies inversely as the distance between these surfaces. If the magnet is made shallow to reduce leakage to a minimum, the winding must be of large diameter in order to acconnnodate the required number of turns of the conductor in the Winding. This large dian'ieter, of course, means that the length of the average or mean turn 'will be great and the more the oliameteris increased to reduce leakage and to We the n'iagnelic circuit a high initial reuctanee the greater this length of'mean turn will be come. A. winding of great weight is thus required and-the consumption of current is necessarily high. It will be understood that in the form of magnet which I have discovered to be well adapted to the purpose, the

length of the winding may be increased to any required extent without increasing its depth so that the length of the mean turn will not, be increased while the lealiagefrom pole to pole will be decreased and the initial reluctance of the magnetic circuit may be eliiciently and economically brought to the desired point.

Referring to the accon'ipaijiying drawings, Figure 1 is a. side elevation partly in section. Fig. 2 is a vertical cross section and Fig. 3 is a top plan of my in'tproved form of lifting magnet. t

In these drawings, 'A is the horizontal core which I make preferablv of circular cross section and of an 3.1123 0 cross section depending upon the weight of material which is required to be handled at each lift. The core A surrounded by the mag netizing winding B, which is properly insulated as shown.

C and C are pole pieces which are at the ends of the core A. The lower or active ends of these pole pieces are extended horizontally in a direction at right angles to the axis of the core and are tapered in thickness so as to preserve as nearly as practicable a cross-section equal to that of the core in a direction at rightangles to the path of the magnetic flux. The active faces of the pole pieces are extended horizontally to a distance very much greater than their thickness. I find that a lifting magnet having this construction of pole pieces has a. much greater lifting capacity in miscellaneous magnetic material than a lifting magnet similar in other respects, but not having the pole pieces similarly extended.

The core of the magnet is preferably made circular in cross section, as this section gives a minimum length of turn in the nmgnet-izing winding. If, however, the pole pieces be given the same cross section, the magnetic flux set up by the magnetizing winding will be caused to flow through a minimum mass of material to be lifted, and this material will be held by a force of attraction many times greater than required to safely lift and hold it while being transported by the magnet. By extending the pole pieces the flux set up in the core is distributed through a greater mass of material to be lifted, and while the flux. density through the load is reduced, with proper design, it still sufticient to safely attract and hold a much larger load. The upper ends of the pole pieces are provided with eye bolts 0 to which chains may be connected for attaching the magnet to the heel; of a crane or equivalent hoisting device.

The ends of the winding B terminate in plugs 14 (only one shown) adapted to receive detacl'iable terminals 05* to which are attached flexible wires o for connecting the winding to a source of electric current. The lower or active ends of the pole pieces C and C are provided with renewable pole shoes C held in place by olts 0 the heads and nuts of these bolts being located in pockets 0 to prevent their li ecoming battered and abraided. The winding B is protected by a cylindrical casing l) which 1 preferably provide with ribs (Z to increase the heat-radiatingsurface The space between the outer surface of the winding and the casing l) is filled with a plastic insulating compound d. The casing D terminates in flanges (Z through which it bolted to the pole pieces C and C by bolts d. These bolts are spaced suiliciently close together to insure a wat r tight joint, their heads being located in the pockets (.Z in the pole pieces, 1 and the nuts are protected by the adjacent ribs (Z.

To protect the lower part of the casing 1) from abrasion with possible injury to the winding, 1 provide a buffer E, preferably made of manganese steel, which is practi cally a non-magnetic material of great toughness. This boiler I prefer to make substantially semi-circular in section so that die sides of the casing and the winding may be protected against impact with cars and other objects when the magnet is being rapidly moved by a crancL The lower ends of the butter are provided with extensions 0' so that the butter may be clamped in place by the pole shoes C, as shown in Fig. l, where the pole pieces and shoes are recessed to receive the ends of the butter. My improved lifting magnet is simple in form and construction. I have actually eonstructed and tested a magnet of this form which weighed less than an annular magnet of approximately the same lifting capacity, and, for the same current consumption and weight lifted, the copper in the magnetizing winding of my improved magnet weighed less than one third as much as that in the annular magnet.

I claiml. A lifting magnet specifically adapted to the hai'idling of miscellaneous products of magnetic material, said magnet having a core, a pole piece depending from either end of said core, and a magnetizing winding surrounding the said core, said winding when energized producing a magnetic flux substantially uniform in direction through the length of said core.

lifting magnet specifically adapted to the handling of miscellaneous products of magnetic material, said magnet having a core, a. magnetizing winding surrouinlin; the said core and a pole piece at either end of said core, substantially all of the mag netic flux set up in said core when said winding is energized passing also through each of said pole pieces. l

3. A lifting magnet adapted to the handling of n'iagnet-ic material, said magnet having a core and a pole piece depending from either end of said core, the lower faces of said pole pieces being wider than the diameter or width of said core, so that the magnetic flux set up in the core may be distributed through, a greater mass of material to be lifted.

l. A lifting magnet adapted to the handling of magnetic material, said magnet having a horizontal core and lllilgllfiilZlllQ winding surrounding said core, and a pole piece depending from either end of said core, said ing in thickness from their junctions with the core downward.

pole pieces ii'icrea-sing in width and decreas-' 5. A lifting magnet adapted to the hana pending from either end of said core, said po e nieces being wider at their faces than tleir junction with said core, but of antially the same area as the cross seoid core.

ting magnet adapted to the handling of magnetic material, said magnet hava core and magnetizing winding'surding said core, and a pole piece de- PPlLllllg from either end of said core, said pieces beingwider at their faces than iei: ioi'ictions with szid core, the cross s ction or said core and each of said "pole l ing substantially uniform at right to the direction of the magnetic flux .l "up by said winding.

'8. in a lifting magnet for lifting miscel- Lius iron and steel products, a horizontal a magnetizing winding surrounding re, and. pole pieces-at the ends of the re, the lower or active faces of said being extended in a horizontal plane distance relatively very much greater thei r thickness.

it lifting magnet specifically adapted handling of miscellaneous products of s eetie material, said lifting magnet havbut a single core and a. single magnetiz- Winding surrounding said core and two pole pieces depending from said core, said polo pieces being so disposed with reference to said core and with reference to each other that they will exert approximately equal att action upon the load to be lifted.

9. In a lifting magnet for lifting miscellaneous magnetic material, the combination of a horizontal core, a magnetizing winding surrounding the said core, pole pieces at the ends of said core, a non-magnetic casing for surrounding and protecting said winding, and a non-magnetic buffer extending between the lower ends of the pole pieces and beneath the casing.

10. In a lifting magnet for lifting miscellaneous material, the combination of a horizontal core, a magnetizing winding surrounding the said core, pole pieces at the ends of the said core, a non-magnetic casing for surrounding and protecting the winding, removable pole shoeson the lower faces of the pole pieces, and a non-magnetic uffer extending between the lower ends 0 the pole pieces and beneath the casing, the said buffer being provided at its ends with extensions adapted to be engaged by the said pole shoes.

Signed at Cleveland, Ohio, this 15th day of July, 1908.-

ARTHUR C. EASTWOOD.

\Vitnesses H. M. DIEM'ER, F. W. J nssor.

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