US2032934A

US2032934A - Electric vibrator

Info

Publication number: US2032934A
Application number: US593585A
Authority: US
Inventors: Walter H Horsch
Original assignee: MASSEY CONCRETE PRODUCTS CORP
Current assignee: MASSEY CONCRETE PRODUCTS Corp
Priority date: 1932-02-17
Filing date: 1932-02-17
Publication date: 1936-03-03
Anticipated expiration: 1953-03-03

Description

March 3, 1936 w. H.. HQRSCH 2,032,934

ELECTRIC VIBRATOR l Filed Feb. 17, 1932 5 Sheets-Sheet 1 Filed Feb. 17, 1952 5 Sheets-Sheet 2 March 3, 1936. w* H, HORSCH 2,032,934

ELECTRIC VIBRATOR Filed Feb. 17, 1932 v 5 Sheets-Sheet 3 j; .6, 752 *JW 25]; I p kQJZUQIZZT March 3,1936. w, H. HORSCH 2,032,934

ELECTRIC VIBRATOR Filed Feb. 17, 1932 5 sheets-sheet 4 *+11 L95 zo? 20 0 200 5r .....J5 20 224 L1 f )Q5 QQ n i March s, 1936. w. H. HORS'CH 2,032,934

ELECTRIC VIBRATOR Filefd Feb. 17, 1952 5 sheets-sheet 5 kyw,

J6 JZ xm Z mai l i ....n 226 www f jmefdr Patented Mar. 3, 1936 infirmer orrficr.l f

n ELECTRIC vrBRA'roR Walter H. Horsch, Wheaton, Ill., assgnor to Massey Concretek Products Corporation, Chicago, Ill., a corporation of Virginia `Application February 17, 1932, Serial No. 593,585

5 Claims.

The present invention relates to vibrators, and is particularly concerned with electric vibrators adapted to produce high frequency mechanical vibrations for industrial purposes. The present vibrators may be used for highfrequency vibration of concrete, sand screens, clay molds, molds for casting metal, and all kinds of molding or casting operations, and I do not wish to limit myself to any particular use for the present vibrators.

One of the objectsl of the invention is the pro-y vision of an improved electrical vibrator of the type disclosed in my prior application, Serial No. 428,995, led February 17, 1930.

Another object of the invention is the provision of an improved commercial form of a vibrator of the class described, `which is adapted to be manufactured economically, which is sturdy, eil'icient and capable of use for a long period of time without necessity for repair.

Another object of the invention is the provision of an improved device for securing the vibrator to the objects sought to be vibrated so that the vibrator may be attached more quickly, with less labor and less expenditure of time.

Another objectof the invention is the provi.

sion of an improved electromagnetic holding device for securing an electric vibrator to a c oncrete form or other object intended to be vibrated by the vibratonby means of which the vibrator can be attached to the form without the necessity for any chains or other securing devices.

Another object of the invention is the provision of an improved assembly, by means of which an electric vibrator and electromagnetic securing device are so arranged that when the current is Aturned on the electric vibrator is drawn over against the concrete form or other article and automatically secured in proper position for vibration of the form.

Another object of theinvention is the provision of an improved hydraulic installation by means of which a mechanical vibrator may be brought into proper position to vibrate any of a succession of concrete forms preferably mounted on carriages.

Another object of the invention is the provision of an improved electric vibrator of the class described having an improved magnetic field construction, by means of which more efficient action is secured.

Other objects, features and advantages of the invention will be apparent from the following description and from the drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the drawings, of five sheets:

Fig. l is a vertical sectional View of a complete installation employing a hydraulic piston and an electric'vibratcr carried by the piston and adapted to be brought into proper position by the hydraulic piston;

Fig. 2 `is a similar view of another modication employing an electromagnetic lifting device for securing the electric vibrator to the article to be vibrated;

Fig. 3 is a side elevational view in partial section showing the specific construction of an improved electric vibrator constructed according to the present invention;

Fig. 4 is another side elevational View in partial section taken from the right of Fig.4 3 showing vthe same vibrator;

Fig. 5 is an elevational view of a vibrator frame, the magnetic structure in partial section showing the coils in elevation;

Fig. 6 is a side elevational view of the frame of Fig. 5 taken from the right;

' Fig. 7 is a top plan View of the frame of Fig. 5 with the transverse electromagnetic ileld structure removed;

Fig. 8 is a plan view of the electromagnetic eld structure which is used in the vibrator of Figs. 3 to 7;

Fig. 9 is a plan view of the face of a magnetic lifting or securing device for securing the vibrator of the previous figures on a concrete form or the like Fig. l0 is a sectional View of the magnetic securing device of Fig. 9 taken on the plane of the line lU-l of Fig. 9;

Fig. ll is a sectional View of the same securing device taken on the planeof the line Il-II of Fig. 9;

Fig. l2 is a diagrammatic view of another form of installation, in which the concrete pipe form is provided with another electromagnetic vibrator.

Fig. 12A is a fragmentary diagrammatic view of a modification.

Fig. 13 is a plan view with the form in sectionshowing one mode of attachment of the improved vibrator to a form;A and Fig. 14 is a diagrammatic View of another form of installation showing a crane for 'lifting the vibrator with its electromagnetic securing device and bringing it into juxtaposition with the form which there are so that the electromagnetic securing device can draw the vibrator into engagement with the form.

Referring to Figs. 5 to 8, the vibrators constructed according to theY present invention are provided with a supporting frame 20, which is adapted to provide a support for the parts of the vibrator and .its casingy and also provided with meansfor securing the vibrator on the form and for permitting the lifting of the vibrator to move it from place to place.

The frame 29 preferably comprises a substantially rectangular cast metal member which is provided with a lifting yoke 2| at one end having an aperture 22 for receiving the hook 23 of any form of lifting device, such as a block and tackle or a crane. The framev 29 is provided with a centrally located opening 23 surrounded by thefour sides 24-21 of the frame in such manner that the fixed and movable elements of the vibrator may be carried by the frame and located inside the opening 23 of the frame. The bottom and

top

24, 26 of the frame 29 are each preferably formed with a lrecess or, socket 28 located on the inside of the

frame members

24, 26 and adapted to receive the fixed

core members

29, 39 which are preferably of substantially U shape.`

The U shaped

core members

29 and 39 are each provided with a pair of parallel legs 3|, 32, joined by a yoke 33 and the yoke 33 is adapted to t in the socket 28. The U shaped core mei-

nbers

29 and 39 are preferably formed of a multiplicity of relatively thin soft iron laminations,

each of U shape, and suiilcient laminations are provided so that the thickness of the pile of laminations in each case is substantially the same or slightly greater than the thickness of the inwardly'extending portion 34 of the

end frame members

24 and 26.

The inwardly projecting formations or lugs 34 are provided with upper and lower at surfaces 35, and they are provided with a plurality of apertures 36 for receiving bolts 31. Metal plates 38 are placed on top of the laminations and below the laminations and secured to the lugs 34 by the bolts 31, the same bolts serving to clamp the laminations 39 together to form the U shaped cores 29'and 39.

The ends of the legs 3| and 32 abut against each other at 49, 4|, forming a closed, and sub stantially rectangular ilxed magnetic core. It should be understood that the term fixed'is ernployed with respect to the frame 20 but, as a matter of fact, the

cores

29 and 39 are also in vibration when the vibrator is in operation, and either one of the magnetic structures may be termed the field and the other the armature, since each reacts against the other one, and both may be energized or polarized.

The

side frame members

25 and 21 are preferably formed with inwardly extending

lugs

42, 43 located above and below the coils carried by the legs 3|, 32 for the purpose of supporting 'the Y transverse metall straps .44 which retain the coils in xed relation with respect to the

fixed cores

29, 39. The straps 44 are secured in place by bolts 45 passing through

lugs

42, 43, and additional bolts 46 serve to clampthe straps 44 against the laminationsof the

cores

29, 39. v

The

side frame members

25, 21 are also pro-l drical member provided with outer threads complementary to the threads of the bore 49, and it is also formed with a substantially cylindrical socket 52 of sufficient size to form a seat for retaining the spring 5| in proper position. The -plug 59 is provided with a kerf 53 for receiving a screw driver in adjusting the plug and a locking plug 54 is also preferably provided for assuring the permanent adjustment of the springs, the purpose of which will be described in greater detail hereinafter.

The locking plug 54 comprises a substantially cylindrical metal member threaded to engage the threads of bore 49, and it may also be-provided with a kerf 55. The locking plug is preferably provided with one or more threaded bores 56 for receiving locking bolts 51, which are threaded into the bores 56 into engagement with the socket plug 59. When the bolts 51 are driven home the plug 59 is very positively secured in its predetermined adjusted position.

Referring to Fig. 8, the movable magnetic structure preferably comprises a pair of

cores

58, 59, each having a yoke 69, 6| -and a plurality of inwardly extending vparallel legs 62-69. The ends of the legs 62-69 abut against each other at 1li- 13. The legs of the two

cores

58, 59 may be maintained in alignment with each other and in i'lxed relation to each other by the clamping members 19 which engage the

legs

62, 66, 69 and 65. In eiect the

cores

58, 59 are substantially E shaped cores with the central leg separated by the slots or spaces 14.

The space 14 is provided for the purpose of preventing the short circuiting of the magnetic flux from one pole of the

cores

58,59 to another pole and assuring the direction of the flux into more usefulI channels, as will be described in detail later on.

The

legs

68 and 69, 64 and 65, 62 and 63, 66 and 61 are spaced from each other a distance sucient to receive the legs 3|, 32 of the

cores

29, 30, leaving an air gap 15, 16, 11, 18 at each side of the fixed

core

29, 39 to permitthe movement of the

movable core

58, 59 during. the vi:- bration of the device. The relative position' of the cores and the size of the air gaps 15-18 may be adjusted by means of the Aadjustable plugs 59 with the springs 5| and the threading of the plugs to the left or the right in the frame 29 de-l termines the position of the springs 5|, and consequently the position of

the'movable core

58, 59 which is supported by the springs.

The

cores

58, 59 are also preferably formed'of a multiplicity of relatively thin soft iron stampings or laminations, as shown in Figs. 4 and 5, and the laminations may be Secured together by a plurality of clamping members 19, 89, 8|

shown in Figs. 3 and 4. The side clamping members 19 may comprise substantially rectangular cast metal members having inwardly extending lugs or anges 82, 93 for engaging above and below the laminations of the E shaped

cores

56, 59. The laminations may also be secured together by rivets or other conyenient fastening means, but they are also preferably clamped by the flanges 82, 83 which extend parallel to the top and the bottom of the laminations of

cores

58, 59.

The clamping members 19 are also provided with substantially cylindrical sockets 84 extending outward and located in registration with the socket 52 in the plug 59. Socket 84 is adapted to receive lthe other end of the spring 5|, one spring being provided on each side of the vibrator. Thecompression of the springs 5| retains the clamping members 19 on the

cores

58, 59, the two springs reacting against each other to urge the other clamping members into engagement with the cores.

The springs 5| are preferably relatively heavy springs, and these springs are preferably sufficiently short and'heavy so that the movement of the armature in either direction is stopped by the spring before the armature comes into contact with the fixed

core

29, 30. In other words, if a relatively light spring is used, the armature may be resiliently supported for movement with respect to theixed core, and vibration will result, but the armature may impact with the core.

IThe force with which a spring of this type resists the movement of the movable core increases with the displacement of the core, and this increase inthe resistive force is greater in a relatively thick and short spring than it is in a light and long spring.

rI he force exerted by the spring may be adjusted by means of the ,plug 50,l and if the springs 5| areof 'the' proper characteristics, the springs maybe so adjusted that they not only tend to j retain the movable core midway between the -eleyments of thefixed core, but the spring absorbs4 the force of. the armature in a predetermined direction and tends to return Athe armature before thearmature comes' Vinto actual impact with the fixed core. n f l Y In somel embodiments f'of'the invention the mechanical 'characteristics of the masses of the fixed core andi-.themovable core'and ythe mechanical characteristics of the springs may be such that the vibrator is `adaptedto vibrate at the natural frequency of the energizing current, which may be any of the standard frequencies employed for alternating -current. Thus, if 25 cycle current is employed',the natural or resonant frequency of the mechanical vibrator would be 25 cycles per second, or if 60 cycle'current were employed, the natural frequency of the mechanical vibrating system might be made 60 cycles per lsecond, or any multiple thereof, depending upon the mode yof use of the alternating current and construction of the vibrator.

I prefer to make the characteristics of the' springs such that the natural or resonant frequency of the mechanical system is slightly below the frequency of the current, such as 40 or 50 cycles per second for a 60 cycle current, in order that the springs may tend to return the movable core from any position of maximum displacement before the core reaches said position. This prevents the movable core from impacting the fixed core because the springs are compressed more quickly to the point where theyl resist the movement of the movable core with a force greater than the force exerted on the core.

. cient results, and either resonant mechanical frequencies may be employed o'r vforced vibra- I tions may be induced. y

The movable cores' 58, 59 are also preferably provided withfsome form of support 'outside' the yokes 60, 6| for maintaining them in proper prey determined positionV transverse .to the yokes 29A and 30. ForY 'this purpose the yokes`|50 and 6| have their 'laminations engaged by the clamping members 80, which may be identical inform.

Clamping member may consist of a cast metal member or plate having a fiat surface for engaging the edges of the laminations and having inwardly extending

flanges

85, 86 engaging above and below the yoke 6|. The clamping member 80 is also provided with a plurality of outwardly projecting lugs 81 formed with a transverse semicircular groove 88 for receiving the rod 89. The lugs 81 may be located at each end of the clamping member 80, and in the middle of the same. and the rod 89 extends transversely of the clamping member substantially parallel to the yoke 6| for supporting this end of the' core 62.

The plate 38 is also provided with outwardly projecting lugs 90-93 located approximately in the four corners of the opening 23 of the frame for receiving the rods 94, 95. Both sides and all four corners of the vibrator may be identical in construction, and therefore only one side or corner will be described in detail. Each of the lugs 90 is provided with a transverse bore 96 extending substantially parallel to the'plane of the frame and adapted to receive a rod 94 or 95. The rodsv 94-95 provide pivots for the securel`ment of resilient metal straps 91|00 for sup- Ving member 80 in engagement with the outer surface of yoke 6|. A similar arrangement engages the outer surface of yoke 60, and the mov-- able core, which may be designated by the letter E and which vcomprises parts 58-59, is thereby supported for movement in a horizontal plane in Fig.- 3` in the .direction of the arrows in Fig. 8. The amount of play in the pivotal joints is sufficient to permit lateral movement of the core, even though the linkage is such as to constitute a substantially closed linkage, for the reason that the amount of movement of the movable core is very small. The movable core M is thus prevented from tilting about the axis of the springs 5| and it is only permitted to move back and forth along the axis of the springs 5|.

The fixed core F, which comprises the

U-shaped members

29 and 30 of Fig. 5. is preferably provided with windings |02|05 located on each of the legs of the fixed core F above and below the movable core M. The windings |02|05 may be k of the winding |04, and that induced by winding In some embodiments of the invention the |03 opposes that-of winding |05. Thus the windings may tend to produce a negative pole at the point 40, as indicated by the minus sign, and a positive pole at the point 4I, as indicated by the plus sign. The two legs 61 and 88 of the movable core M are preferably embraced by a winding |06, and the two legs 63, 64 'embraced by a winding |01.

The windings |08 and |01 may be connected in parallel or series and energized from the same source, but the connection and direction of winding `is preferably such that they tend to produce flux in oppositedirections and thereby cause the formation of a magnetic pole at the points 1|, 12.

and may be negative at .any particular instant,

These poles will naturally' be' of the same polarity as indicated by the minus signs in Fig. 8. The windings IUS- |01 are preferably energized from a source of alternating current, and consequently the polarity of the pole pieces 1|, 12 will be periodically changing at the same frequency as the frequency of the source of current. When the poles 1|, 12 are negative, the poles 10, 13 will naturally be positive, since the magnetic circuit is completed by the outer legs of the core M. vSupposing the polarity to be as indicated in Figs. and

= 8-at any given instant, this would result in an attraction between the poles 10 and 40 andpoles 12 and 4|, since they are oppositein sign, while a repulsion would take place between poles and 1| as well as poles 13 and 4|,

It'will be evident that if the xed core F is polarized as shown by a source of direct current, and alternating current is applied tothe windings of the movable core M, the movable core will be caused to vibrate back and forth periodically in the direction of the arrows of Fig. 8, and the extent of this movement will be limited by the clearance provided by the action of the springs 5|. If desired, in some embodiment of the invention, the cores may be provided with resilient bumpers, or they may be permitted to impact against each other, but one of the objects of the invention is the provision of a device which will produce mechanical vibration with a minimum amount of noise and wear on the parts of the vibrator, and consequently the springs are so proportioned and adjusted that they prevent impact.

The windings of the vibrator may be energized according to any of the` systems disclosed in my priorapplication, Serial No. 428,995, filed February .17, 1930, for Method and apparatus for treatment of concrete and the like, and the present application is a continuation in part of 'said prior application.

The windings on the fixed and movable cores are preferably iixedly secured in place and insulated from the cores by fiber plates |08, |09, ||0 (Fig. 4). The windings are wrapped with insulating tape, and the connections are taped to the parts of the vibrator to prevent wear on the leads. 'IIhus the leads ||0' are taped or wrapped at to secure them to the 'metal strap 91.` The transverse straps 44 effectively block the windings |02|05 in fixed relation'with respect to the fixed core F by engaging the ber plates I0. Plate 38 may be formed with an outwardly extending flange ||2 for engaging the fiber plate |09 below the winding |04.

'Ihe windings on the movable core M may likewise be secured in place and suitably insulated, and the respective windings may be grounded to the frame at their mid-points between two coils. This provides a balanced construction in which a short circuit on lone winding merely results in the disablement of half of the windings, and there is less danger of burning out of the entire windings.

` The frame 20 is preferably formed with a substantially fiat surface H3, H4 on each side bordering the entire frame for receiving a complementary flat attaching flange ||5 carried by a sheet metal cover I|6. The cover 6 may be stamped out of-sheet metal to substantially the shape shown in Fig. 4 to enclose and protect the mechanism of the vibrator, audit may be secured to the frame by a plurality of screw bolts ||1. A similar cover ||8 upon the other side of the frame 20 completes the casing.

The frame 20 is also preferably provided with anaperture ||9 at one side, leading to a depressed socket |20 formed in the outer surface of the frame and adapted to receive the laminated ber plates |2|. A socket fitting |22 may be formed of cast metal and provided with outwardly projecting attaching flanges |23 and with a socket |24 for receiving the complementary socket fitting |25.

Referring to Fig. 4, it will' be noted that the socket |24 is substantially rectangular in shape but is provided with a groove |26 for receiving the pointed formation |21 on the complementary fitting |25, so that the plug |25 can only be inserted in one position, and the fiber plates |2| may be secured to the frame by means of screw bolts |28, and the ilber plate |2| may carry a plurality of male contact prongs |29. The con' nection plug comprises a fiber support consisting of a plurality of plates of insulating fiber |30 which carry a plurality of female contacts |3| for engaging the male contacts |29. In the presi the casing |26 slopes downward and outward so i that the yoke |31 may come into wedging engagement with it and fixedly secure the connector in place so that there is no possibility of the -connector being dislodged bythe vibration.

- The contact prongs |29 and connectors I3! are, of course, provided with appropriate leads extending in the first place to the coils and in the second place out the tubular fitting |38 into the l rubber covered cable |39 leading to the source of Supply.

The frame 20 is preferably provided with the laterally projecting legs |40|43 terminating in attaching flanges or feet |44-.|41, which are provided with apertures |48. The feet |44 may be provided with a substantially at lower surface |49 for use in engaging a at form and the legs |40, |4| and |42, |43 may be separated by the angular surfaces |50, |5|. The angular surfaces |50, 5| are adapted to engage the curved parts of a curved form when it is desired to secure the vibrator to the form in some manner similar to that shown in Fig. 13.

Referring to Fig. 1, this is an improved vibrator installation in which the vibrator V is adapted to be brought intoengagement with a number of different objects or forms to Vbe vibrated, succes.- sively, and the form F is preferably supported upon a truck or carriage |64.

Any suitable form oftruck may be utilized, but it is preferable to use a flanged wheel truck mounted upon tracks |1| so as to 'bring the truck into a predetermined position over the vibrator V.

i The vibrator V In order to enable the'truck axles |12 to clear the vibratorV without movingthe .vibrator so far as would otherwise be necessary, the platform of truck |64 is provided with anginverted table consisting of a plate |13 which is supported on the lower side ofthe truck by-a plurality of legs |14, the legs beingriveted to the truck and plate. is adaptedto engage the lower surface of plate |13 and lift the truck |64 vand form-F until the major portion of the weight or all of the weightis taken off the wheels 1| 68,'after which'the operation of the vibrator will effec- A tively place-the truck |64, form F, and the concretein the form in a state of vibration.

With a vibratorof the type shown in Figs. 2 and 3, the truck, form and concrete would be vlbrated by virtue of theinertia effect of the movable core M, but in some embodiments of the invention the movable core M may be directly connected to the plate |13 so that direct mechanical impulses are transmitted to the truck, form and concrete, the frame of'the vibrator reacting against its support.

, In order to movablysupport the Vibrator V in position to be brought into engagement with successive trucks, it is preferably mounted on a tubular piston |15, which is'mounted for reciprocation ina cylinder |16. The cylinder |16 comprises a closed tubular member mounted in a cast iitting |11, -which is provided with a packing |18 and a gland |19 for compressing the packing.

The pipe |80,-which communicates with cylinder |16, leads to a source of supply of hydraulic fluid, such as oil or water, through the pipe' |8| and control valve |82, but in some embodiments of the invention a source of compressed air may be used. The pipe |83 communicates with pipe below valve |82, and is provided with a release valve |84. When the valve |84 is closed and the .valve |82 is turned on, the piston |15 is urged upward by the pressure in cylinder |16, and the vibrator. V is brought into engagement with the plate |13 of the truck. The valve |82 may be closed when `the vibrator has reached the proper position, and the vibrator may be turned on and the concrete subjected to high frequency vibration to improve its characteristics and cause it to ow into place in the form.

Many other articles may be subjected to vibration besides the concrete, which has been -selected toI illustrate the invention.

`When the valve |82 is closed, the vibrator V will be maintained in fixed elevated position, but

when the valve |84 is open thepressure will vbevibrator will slidably supporting the bearings v new truck with another form m y be brought into proper position. A suitable stop may be provided for the truck |64 so that when it is moved into engagement with the stop it is located with its plate |13 inpredetermined position under the 5 truck, and if one vibrator is utilized it is preferably symmetrically located with respect to the contents of the form, butany number of vibrators may be utilizedv and operated synchronously, as described in my other applications. 10

Referring to Fig. 2, this is another diagrammatic illustration of the same truck which is employed with another illustration in which the vibrator V is adapted to be attached to the truck |64 by means of an electromagnetic securing de- 'vice |85. In such case the metal plate |13 may act as an armature and the electromagnetic securing device is 'provided with attaching flanges when'the electromagnetic securing device |85 is 2s energized the armature |13 is within the range of action of the electromagnet |85, and the vibrator Vis drawn up into engagement with the plate ,|13 and heldin placev while the vibrator is operated.

It will be evident that the present system, using an electromagnetic securing device, eliminates much of the labor of securing the vibrator upon successiveforms, such as would be entailed by the structure of Fig. 13, and the mere closing of the circuit of the electromagnet causes the vibrator to move into securement with the truck or the form. The vibrator V1 and electromagnet |85 may be energized through the conductors |90, |9|, each including a plurality of appropriate leads extending to one or more control switches |92. The control switches may be provided with a single actuating member whereby both the vibrator and electromagnet may be turned on at the same -trally located opening 23| so that the vibrator may be brought into direct engagement with the yform itself without vibrating the truck, except such vibration as is effected incidentally. Either type of securing device may be utilized, and the spider-like frame may be secured to a plate 232 which may consist of the bottom of the form, or which may consist of an extra plate loosely placed upon the topv of the truck. The'vibration is more effectively transmitted to the form and concrete by this direct mode of attachment.

Referring -to Figs. 9 to 1l, these are detailed views of the electromagnetic securing device, which may be indicated in its entirety by the numeral |85. The electromagnet preferably lcomprises a metal casing |93 which may be circular or oval in plan, but which is preferably substantially rectangular in shape, and which is provided with Vthe attaching flanges |86 having apertures |94. The casing |93 is provided with a centrally located pole piece |95, which may be substantially rectangular in plan and which forms 70 one of the poles of the magnet. The outer walls |96-'-|99 form the other pole of the' magnet and also enclose the coils 200 and prevent leakage. The space between the central pole |85 and the walls |96'|99 may be filled by the energizing 75 coils 200, which are suitably insulated from the metal of the electromagnet by means of fiber plates 20|-204. The leads 205, 206 from the coils 200 may be brought out through the same connector |29, |3i, which is used forthe vibrator, or the leads may be broughtbut through any suit-able form of protecting cable.y

The windings 200 are preferably secured in place by the

transverse bars

201, 208 of nonmagnetic metal, such as brass, or in some cases 'magnetic metal may be utilized, such as steel,

provided the bars are so small that they will be saturated and only short circuit a small portion of the flux. The

bars

The surfaces 2|5, 2|6 of the walls and central pole piece of the electromagnet may be made substantially ilat when the magnet is intended to engage a at plate |13 which acts as the armature, but when the electromagnet is intended to be used with curved pipe forms such as the form 2|1 of Fig. 14, the face of the electromagnetic securing device |85 may have its surfaces 2| 4-2I6 complementarily curved to the pipe 2| 1.

Where the electromagnuet is intended to come into direct engagement with a metal pipe form or some other form which cannot be conveniently constructed of laminated metal, the elec-1 tromagnet is preferably energized from a source of direct current for the reason that the use of alternating current would unduly heat the form on account of the eddy currents induced in the form. v

In some embodiments of the invention, such as Fig. 12, the pipe form 2|8 may have permanently secured to it a'laminated armature 2|9 which is adapted to be engaged by the electromagnet |85 and utilized for the armature of the electromagnet. In such case, the laminations oi the armature 2|9 preferably extend sub- Istantially radially with respect to the center of the pole piece |95 in such a manner as to permit the passage of ux from the inner pole |95 to the outer wall most readily, but economical conv struction may dictate a change from the purely radial lamination inconstructing a laminated armature for the magnet |85.

Where such laminated armature is provided on the form the electromagnet may be energized by alternating current, and the connections A and control 'of the electromagnet and vibrator are greatly simplified bysuch an arrangement, since both the magnet and vibrator may be controlled by a single switch.

Referring toA Fig. 14, this is a modified form of installation in which the vibrator V is provided with an electromagnetic securing device having a cylindrically formed pole piece for engaging the pipe form 2|1. The vibrator is supported by means of a hook 23 which is carried` by the lower pulley 220 of the hoisting tackle 22|, the upper pulley 222 being carried by the en'd 223 of a crane 224. The arm'of the crane 2211s rotatably mounted in a bearing 225 oi a base 226 which is mounted upon casters or wheels,

221, the weight of the base being suillcient to support the vibrator in the position of Fig. 14.

The electromagnet |85 may be energized by direct current through leads 228, and the vibrator V may be energized through leads 229 which are controlled by switches 230 interposed between the devices and the source of supply.

It will thus be observed that I have invented an improved electric vibrator which is adapted to be utilized for producing high frequency mechanical vibrations in concrete or any othersubject to which it may be desirable to apply vibration. The present vibrator is capable of applying a larger amount of power, the vibrations are direct mechanical impulses in a predetermineddirection, and this power may be applied most eiciently and with a minimum amount of noise.

The vibrator is capable of being applied to various kinds of forms and capable of being easily manipulated, and the installation may be so arranged that the vibrator is automatically attached to the subject-matter by an electromagnetic securing device, thereby eliminating the necessity for fastening ropes, cables, chains or the like. The vibrator may also be moved into predetermined position by mechanical appliances such as a hydraulic piston or a crane, so that a number of objects may be vibrated successively with a minimum amount of labor.

The electromagnetic securing device may be actuated by the same switch which closes the circuit of the vibrator so that the vibrator is simultaneously secured and energized and the concrete form or other object immediately subjected to vibrations.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the claim is new and desire to secure by Letters Patent of the United States, is:v

1. In an apparatus for vibrating concrete or the like, the combination of a form with an electric vibrator adapted to produce vibrations of predetermined frequency, an electromagnetic securing device carried by said vibrator, `and an armature for said securing device carried by said form whereby said vibrator is automatically secured to said form when said securing device is energized and the vibrator is brought into sumcient proximity with said armature.

2. In an apparatus for vibrating concrete or the like, the combination of a supporting base with a movable crane arm carried by said base and electric vibrator means carried by said crane' arm and attached to said vibrator for supporting said vibrator, a. magnetic securing device carried by said vibrator, and a metal form adapted to be engaged by said magnetic securing device when the latter is energized to hold the vibrator on the form.

3. In an apparatus for vibrating concrete, the

combination of a form havinga metal part with havingamovingbodydwdbvvirtueofitsu inertia to induce vibrations in a member to which the vibrator is secured, with a member to be vibrated, said member having a paramagnetic.

part serving as an armature, and electro-magnetic means for securing said vibrator to said amature comprising an electro-magnet carried by the vibrator,fwhereby the vibrator is i'ixedlyk secured to the member to be vibrated when the electro-magnet is energized and brought into 10 sufcierit proximity to the amature.

WALTER H. HoRsCH. lm