US1932520A - Method and apparatus for treatment of concrete and the like - Google Patents

Description

@nt. 31, 1933. w. H. HOR$CH 1,932,520

KETKOD AND APPARATUS FOR TREATMENT OF CONCRETE AND THE LIKE Filed Feb'. 17, 1950 5 Sheets-Sheet 1 Oct. 31, 1933.

IETHOD AND APPARATUS w. H. H ORSCH FOR TREATMENT OF C ONCRETE AND THE LIKE Filed Feb. 17; 1930 5 sheets sheet 2 Oct. 31, 1933. w. H. HoRscH METHOD AND APPARATUS FOR TREATMENT OF CONCRETE AND THE LIKE Filed Feb.- 17, 1930 5 Sheets-Sheet 5 z wmm aw Oct. 31, was.

\N. H. HORSCH IE'IHOD AND APPARATUS FOR TREATMENT OF CONCRETE AND THE LIKE.

Filed Ffeb. 17. 1930 5 Sheets-Sheet 4 Jaw/wk? Qct? 31, 15 933 I w H, HQRSQH 1,932,520 Q METHOD AND APPARATUS FOR TREATMENT OF CONCRETE AND THE LIKE Filed Febh 1'7, 1950 5 Sheets-Sheet 5 Patented Oct. 31, 1933 UNITED STATES PATENT OFFICE IHETHOD AND APPARATUS FOR TREAT- ltIENT OF CONCRETE AND THE LIKE Application February 17, 1930. Serial No. 428,995

24 Claims.

The present invention relates to the method and apparatus for the treatment of concrete or the like, and is particularly concerned with the manufacture of monolithic concrete articles or structures in which it is desirable to provide concrete of particularly high grade and strength. It should be understood, however, that certain features of the method and apparatus are of general application to all forms of concrete or other cementitious mixtures, and the term concrete as used herein is not limited to any particular materials, but in its broadest sense includes all cementitious materials to which the invention may be applied.

It is highly desirable in the making of concrete and other cementitious materials, that the finished material be as dense as possible, or conversely that the proportion of voids be made as lowas possible. The strongest and most durable concrete is characterized by a low proportion of voids and a high density, and consequently, the cement, sand and coarse aggregate should be chosen with a view to the filling of the voids between the particles as far as it is possible, and the generally accepted theory is that the cement should fill the voids between thesand particles -while the sand and cement should fill the voids between the course aggregate, such as gravel or crushed stone.

In the making of concrete according to the prior art, the principal methods of producing a compact concrete have been the tamping of a relatively dry mix or the use of a wet flowing mix,

but the use of excessive water weakens the finished concrete and increases the percentage of voids in the finished concrete over the dry mix. The wet mix is, of course, capable of flowing more readily into every part of the form, but a large pa tor the voids between the aggregate is filled wi h water as well as air bubbles, and when the concrete is set and cured, more voids will generally be found in concrete made with a flowing mix than with a relatively dry mix.

According to the prior art, the dry mix has been tamped by hand or by mechanical tamping devices, and it has also been found desirable to spade the concrete in the form near the surface to bring the cement grout to the surface adjacent the form, and to space the coarse aggregate from the form to give a smoother surface.

Such tamping operations require the employment of additional labor, and the process offilling the forms is slowed up considerably due to the fact that the concrete cannot be fed faster 5 than it is tamped, and where the forms are very deep and narrow, there is no certainty that they are properly filled unless the filling and tamping, or spading is carried on carefully and slowly with a fairly wet mixture.

The description of the present method and ap- 60 paratus in connection with ordinary concrete is, of course, to be regarded as exemplary of but one of the uses and forms of the method and apparatusrespectively, and the invention may be used with all kinds of cementitious mixtures for produ ng a product with improved characteristics more economically.

One of the objects of the present invention is the provision of an improved method and apparatus for treatment of concrete, whereby a drier mix may be used to manufacture precast units of a better quality.

Another object is the provision of an improved method'and apparatus for treatment of concrete, whereby the finished and cured concrete which is produced, has a lower percentage of voids and a higher density than-the concrete of the prior art.

Another object is the provision of a method and apparatus of the class described, which is capable of producing precast units of greater strength and better finish than the practice oi. the prior art has produced.

Another object is the provision of an improved apparatus which is capable of speeding up the compact filling of the forms and eliminating the labor usually required for tamping operations.

Another object is the provision of a concrete form vibrator, which is compact, serviceable, efficient, economical, and capable of produced improved characteristics in the concrete treated thereby.

Another object is the provision of a concrete form vibrator having a minimum of moving parts, and capable of producing a positive vibrating thrust upon the work..

Another object is the provision of an improved method of treatment of concrete, by means of which the electrical energy which is usually readily available may be most directly translated into direct mechanical action upon the concrete to promote crystallization, compact the concrete, increase its density, decrease voids, and generally improve the characteristics of the concrete.

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

It should be noted that the present method of treatment of concrete is capable of being carried out by means of any of a number of different forms of apparatus, and the apparatus illustrated in the accompanying drawings is merely exemplary of some of the preferred forms of apparatus for carrying out the present method.

Referring to the drawings:

Fig. 1 is a plan view of the apparatus applied to the form for reinforced concrete pipe;

Fig. 2 is an elevational view of a part of the same apparatus;

Fig. 3 is a plan view of another form of apparatus arranged to induce vertical vibrations in a form for concrete cribbing or posts;

Fig. 4 is a diagrammatic view of one form of electromagnetic structure and electric wiring arrangement employing alternating current in the coils of the field structure with or without direct current impressed upon the armature coils;

Fig. 5 is a similar diagrammatic view of an arrangement which employs one-half the wave of an alternating current source on one of the field coils, with the other half of the alternating current wave on the other field coil, both with or without the use of direct current for polarizing the armature;

Fig. 6 is a similar diagrammatic view showing the use of alternating current in the field coils with a polarized armature consisting of a permanent magnet;

Fig. 7 is a similar diagrammatic view of a socalled dynamic type of vibrator, employing a moving coil for an armature and a field coil for polarizing the field structure, one of which coils may be energized with alternating current, and the other with direct current;

Fig. 8 is a sectional view of a preferred form of vibrator taken on the plane of the line 8--8 of Fig. 9;

Fig. 9 is a similar view taken on the plane of the line 99 of Fig. 8;

Fig. 10 is an elevational view of the mechanism of another form of vibrator with the casing shown in section on a vertical plane;

Fig. 11 is a similar view of another modified form of vibrator with a different form of spring mounting for the vibrating field structure;

Fig. 12 is another similar view of another modification;

Fig. 13 is an elevational view of the mechanism of another modification with the casing shown in section on a vertical plane.

The method of the treatment of concrete is best illustrated by reference to one of the forms of apparatus used in carrying. out the method, such as for instance, the vibrator of Fig. 10, which may be secured to a concrete receptacle or form as shown in Fig. 1. The concrete form 20 is, of course, regarded as exemplary of one of the many types of forms or receptacle to which the present apparatus may be applied for treating concrete, and the present form includes a pair or semicylindrical outer form members 21 and 22, which are usually provided with laterally projecting flanges 23 and 24 for securing the halves 21 and 22 of the form together by means of bolts 25.

Since the present form is illustrated in connection with the casting of a concrete pipe, the form also includes an interior cylindrical form member atically illustrated at 26, but which may consist of any type of interior form for a pipe.

The vibrators used in carrying out the present method preferably consist of two or more rela- 10) 27 and 28, one of which is fixedly secured to the concrete receptacle or form which is to be placed in a state of vibration, and in its simplest form the concrete form itself may perform the function of one of the electromagnetic members provided the form is made of magnetic material.

The electromagnetic structures 27 and 28 are customarily called the field core" and the armature", and either one of these structures may be made the part which moves with respect to the other part fixedly carried by or forming a part of the concrete form, and consequently, the terms field core" and armature may be employed interchangeably in describing these parts, although the term armature" is customarily applied to the smaller or moving part only.

In order to adapt the vibrators to be quickly and firmly applied to concrete forms, such as those used for pipes, one of the electromagnetic structures 28 is preferably fixedly secured to a metal plate 29, which is formed with a pair of diverging flanges 30, 31. The diverging flanges 30, 31 of plate 29 are capable of embracing a pm tion of the cylindrical form 20 for concrete pipe and engaging any of a plurality of different sizes of forms in the same manner.

In order to reinforce the plate 29 and secure it to the vibrator, the form engaging plate 29 is preferably provided at its rear side with a pair of transverse metal frame members 32, which may be secured to the plate by a plurality of right-angled brackets 34 and a plurality of rivet-s 35 securing the brackets to plate 29 and to frame members 32, 33. The frame members 32,33 are spaced vertically a sufficient distance to receive between them a casing 36 of the vibrator, and

the casing 36 may be fixedly secured to frame members 32, 33 by a plurality of rivets 3'7.

The plate 29 is also preferably provided with a pair of right-angled brackets 38 for securing thereto an attachment chain 39, and the opposite edge of the plate may be furnished with a vertical frame member 40 for providing a mounting for a threaded eye bolt 41, having a hand wheel 42 and having an attachment chain 43 attached to the eye of said bolt.

Each of the attachment chains 39, 43 may consist of any type of chain orother flexible member, such as a strap or cable, which is capable of firmly securing the vibrator unit upon the form, and the ends of chains 39, 43 are preferably provided with the hooks 44, 45 having opposed Jaws 46, 47 capable of receiving the flanges 23, 24 and securing the vibrator unit on the form 20 when the slack in chains 39, 43 is taken up.

It will be evident from Figs. 1 and 2 that when the hooks 44, 45 are disposed upon the flanges of the pipe form 20, the slack in the chains 39, 43 may be taken up by turning hand wheel 42 in a clockwise direction, which will cause the eye bolt 41 to progress to the right in Fig. 2 through the frame member 40, tensioning chains 43, 39.

The form engaging plate 29 will automatically align itself upon the cylindrical form 20 by means of the diverging flanges 30, 31, and the electromagnetic structure 28 will thus be fixedly secured to the concrete receptacle or form 20, so that any direct mechanical impulse which is impressed upon the electromagnetic structure 28 will be transmitted directlyto the form 20 and thence to the concrete or other cementitious material therein.

It is also highly desirable to provide the vi brator unit with a supporting chain 48 connected -75 tiveLv movable electromagnetic structures (Fig. to the top of the unit at some central point 19;

substantially above the center of gravity, so that the unit may be hung vertically from the crane or other support and swung into place upon the successive concrete forms to be attached thereto during the treatment of the concrete in each form.

The direction of vibration of the form depends upon the structure of the particular vibrator and its mode of attachment, and another form of attachment is illustrated in Fig. 3, in which the preferred form of vibrator 49 is fixedly secured to the top of one or more concrete forms for cribbing or posts, the forms being supported upon a spring truck, rubber plugs, or any other form of support which permits the vibration of the form. The arrangement of Fig. 3 is peculiarly adapted to produce vertical vibrations in the cribbing form, and the vertical vibrations appear to be peculiarly eifective in the compacting of concrete and the elimination of the voids by vibrating the particles into intimate contacting relation and driving out the air as evidenced by a boiling up of air bubbles during the vibrating operation.

The present method of treatment may be carried out after the form has been filled, but it is not deemed desirable to utilize any vibration after the initial set has begun and ordinarily, the method of treatment by vibration should be begun as soon as the filling of the form commences and continued simultaneously with the filling of the form to efiect the compacting and settling of the concrete, to aid its crystallization and to eliminate voids between the particles.

The present vibrating devices are also capable of utilization for effecting or improving the mix of the concrete or the conveying of concrete or other material in a substantially dry state through inclined conduits, the continuous vibration placing the particles in a state of agitation and permitting -them to move more readily through a conduit or into a form.

Referring to Figs. 4 to 7, the electromagnetic structures 27 and 28 are here illustrated in connection with a plurality of exemplary forms of energizing windings, and it should be understood that any one of the forms of windings illustrated in these figures may be employed in any one of the various vibrators described hereinafter.

Referring to Fig. 4, the field core structure 28 comprises a field core of electromagnetic material, such as soft iron larninations, having a pair of opposed poles 50, 51, spaced sufficiently to receive the armature 27 and leave the air gaps 52, 53. In the present embodiment, the field core 28 is a substantially rectangular structure for the purpose of providing a coil receiving leg 54, at each end, and to leave sufiicient space 56 inside the rectangular electromagnetic frame for receiving the coils? The armature 2'7 is preferably movably mounted with respect to the field core 28, and consequently, is diagrammatically illustrated with a pivotal mounting consisting of a pin 57 passing transversely through the field core 28 and armature 27, the armature being located in a socket 58.

In order to increase the strength of the mechanical impulses generatedby the vibrator, the armature 27 is preferably polarized, and for this purpose, a permanent magnet may be used as in Fig. 6, or the polarization may be generated and maintained by means of a direct current energizing coil 59. v

The two legs 54 and 55 of the field core are also preferably provided with energizing coils 60, 61, which are wound in the same direction with respect to the magnetic circuit formed by the field core 28, so that the pole 50 will be a positive magnetic pole when the pole 51 is a negative magnetic pole.

The coil 59 may be energized by direct current in such manner that polarity of armature 2'7, adjacent the air gaps 52, 53, is always the same value, either positive or negative, and consequently, when the coils 60 and 61 are energized by alternating current, the polarity of the field core 28 with respect to the armature is periodically changed.

- The present apparatus is preferably employed with a standard alternating current source, the relatively high frequency of 60 cycles per second being preferred, but it should also be understood that the device may be employed with a lesser speed of vibration on other sources of alternating current, such as 25 cycle, and by particular arrangements of the energizing coils and other apparatus, multiples of 60 cycle alternating current vibration may also be secured.

Referring to Fig. 5, the armature 27 is here illustrated in spaced relation to the field core 28 to indicate a movable mounting of the armature with respect to the core, and this armature 'may also be energized by a direct current coil 59. 1 5

The field coils 60, 61 may be energized by alternating current with the inter-position of two rectifiers 62, 63, such as copper oxide rectifiers, so arranged that one-half of the wave of the alternating current acts on one of the coils 60, 11 while the other half of the wave of the altematcurrent acts on the other coil 61.

The rectifier 62 will thus prevent the .passage of current through the coil 60 while the current is acting upon the coil 61, and in effect the coils 5 60 and 61 will be alternately energized to change the polarity of the field core 28 and successively induce flux in opposite directions. The armature 27 may be movably mounted in any convenient manner, but it is preferably provided with means for polarizing the armature, such as a permanent magnet or the direct current energiz'ing coil 59.

Referring to Fig. 6, this modified form of energizing arrangement includes an armature 27 consisting of a permanent magnet which is movably mounted with respect to the field core 28. The field core 28 may be provided with field coils 60 and 61, and the coils 60 and 61 are preferably provided with a plurality ofseparate taps, 'so that they may be connected in series or in parallel to vary the effect of the coils as desired for any particular installation.

The coils 60 and 61 should be wound or energized in such manner as toinduce flux in the same general direction about'the magnetic field core 28. Thus, if the coils 60 and 61 are wound in the same direction proceeding about the magnetic circuit, they may have their ends connected together in series in the same direction as in Fig. 6, but if the coils happen to be wound in the reverse direction, as illustrated in Fig. 4, then the connections must be reversed in order to induce flux in the same direction. The proper connection of the respective coils may be determined by testing the polarity of the core when the coils are energized, after which the coils should be connected, so that their magnetometive force acts in the same direction in the magnetic circuit 28. r

Referring to Fig. '7, the energizing arrangement illustrated in this modification comprises the dynamic or moving coil type. In this embodiment, the direct current coil 59 may be mounted upon any convenient portion of the field core 28, but is preferably located upon the central leg 62', so that the coil 59 is embraced by the other legs of the field core 28. The core leg 62' preferably extends out between the poles 107 and 108 of the field core 28, forming a pole piece 65 which may be surrounded by a movable coil 66 carried by any form of support, such as a non-magnetic or insulating sleeve 6'7. One of the coils 59 may be energized by direct current and the other coil 66 energized by alternating current or vice versa, and the resulting interaction of the flux generated by the coils 5 9 and 66 will produce relative movement between the armature coil 66 and the field core 28.

It has already been pointed out that either the armatures 27, 67 or the field core 28 may be fixedly mounted upon the concrete receptacle or form, and ordinarily in a portable device the smaller of the two magnetic members will be fixedly secured to the form; so that the heavier magnetic member may be utilized as an inertia member against which the flux reacts in producing a direct mechanical thrust against the concrete and form. The exact direction of vibration depends upon the mode of attachment of vibrating device and the direction of motion of the field core with respect to the armature. For instance, in Fig. 4, the field core 28 will oscillate about the pivot 27 inducing corresponding vibrations in the concrete form, while in Fig. '7, the force exerted on the dynamic coil 66 tends to draw the coil upon the leg 62 or move the coil from oil the leg, thereby producing vibration along the general direction of the leg 62.

Any one of the forms of energization described in Figs. 4 to 7 may be utilized in any one of the electromagnetic vibrators described herein and the present invention includes all the permutations and combinations of the respective structures and coil arrangements described.

The method of treatment of concrete by means of the use of electrical energy may be described in detail as follows.

Referring to Fig. 4, and assuming that the armature 27 is fixedly secured to the concrete form, the electromagnetic body 2'7 may be energized by direct current for the purpose of inducing an electromagnetic fiux in a predetermined direction. For instance, the direction of current and the direction of the windings 59 may be such that a plus magnetic pole is induced near the outer end of armature 27. This polarization is preferably maintained by maintaining the energization of the coil 59 with direct current, but in some embodiments of the invention the armature 27 may be magnetized directly by the other energizing coils or by magnetism induced by connection of the armature with other parts of the electromagnetic circuit.

The coils 60 and 61 may be energized by alternating current, preferably of the standard line frequency, so that the apparatus can I be used without auxiliary generators or converters. For instance, here the coils 60, 61 are energized by 60 cycle alternating current. The direction of energization of these coils will be changed one hundred and twenty times per second, and consequently, the direction of the electromagnetic flux induced by the coils will be changed at the same rate and vibration of the field core 26 will result.

For instance, assuming the initial energization is such as to induce a flux in the field core 28, so that a plus pole is produced at the pole 50 and a minus pole at the pole 51, the operation will be as follows.

The interaction between the positive fiux issuing from the pole 50 and the positive fiux from the armature 27 will cause the armature to repel the pole 50, producing a direct mechanical thrust upon the field core 28. This action is increased by the interaction or the positive flux from armature 27 and the negative pole 51 which tends to 'attract the armature, and as a result the field core 28 is rotated in a clockwise direction with respect to armature 27. I

This mechanical movement of the field core 28 is so quick that dueto the inertia of the field core 28, the fiux reacts against the armature 2 7 and produces a direct mechanical thrust upon the concrete form or receptacle, and as a result the form and concrete aggregate are jarred in a predetermined direction. When the current reverses in the alternating current coils, flux is induced in the opposite direction producing a direct mechanical thrust upon the concrete form in the opposite direction.

It will be evident that the same result may be accomplished by the use of a direct current of a pulsating type or by a direct current which is intermittently broken, but alternating current is capable of producing periodic reversals of flux and periodic vibration of the two electromagnetic parts with a direct mechanical vibration of the concrete form.

It should be understood that in the portable type of vibrator, the movable magnetic member will be of sufficient weight so that it may induce vibration in the concrete form by virtue of the inertia of said member, but if desired, the electromagnetic member may be of relatively light weight if it is arranged so that the concrete form rests directly upon it, or if the electromagnetic member, such as the field core 28, is firmly anchored to some fixed body, such as a foundation.

The operation in both cases is fundamentally the same, except that in the latter case, the form is vibrated by'the reactionof the fiux against the electromagnetic body which tends to main-' tain its state of rest due to the inertia of its own weight and the weight of any body to which it is connected.

In some embodiments of the invention, the two electromagnetic bodies may be resiliently mounted in such manner that the natural period of vibration of the inertia body and the springs corresponds approximately to the period of the alternating current, but since a commercial vibrator must be used upon all types of different forms, the natural period of vibration of the complete assembly will be changed by installation of the vibrator upon a heavier or stifi'er form, and consequently, the vibrations which are induced in the concrete form are generally of the type termed "forced vibrations".

Ii The relatively quick mechanical impulses tween the larger particles, producing a more in series or multiple.

compact concrete and filling every portion of the The vibration also tends to bring to the surface of the concrete at the form, a relatively thin layer of grout or richer mixture, so as to produce a smoother precast unit, and it is believed that the vibration has a beneficial effect upon the crystallization of the materials used in the manufacture of concrete.

Referring to Figs. 8 and 9, these are sectional views of a preferred form of vibrator, which is capable of producing vibrations of a similar type for the treatment of concrete or the like. The

The frame member 69 comprises a substantially rectangular member extending at right angles to the frame member 68, and is preferably provided with guide lugs 75 and screw bolts '76, or other convenient fastening means for fixedly securing one of the parts of core 70 to the frame. In the present embodiment, the core 70 may consist of a pair of substantially u-shaped members, each having a yoke 7'7 and a pair of legs '18, '79. If desired, the length of the legs 78, 79 may be such that an air gap exists between' the ends of the legs, but I prefer to make the legs '18, 79 of such length that they may form a practically continuous magnetic circuit when they are secured inside the frame 69 as shown in Figure 9. Each of the legs 78 is provided with an energizing coil 81 and each of the legs 'I9 with an energizing coil 81a, and the coils are preferably provided with a plurality of taps for connection The coils 81 and 81a upon one-half of the core 70 are wound and energized in such manner that they tend to produce flux in the same direction in the U-shaped core. The coils 81 and 81a upon the other half of the U- shaped core are so wound and energized that they tend to produce flux in the opposite direction, and the coils should be so arranged and connected that similar parts of the symmetrically opposed core halves are of the same polarity. That is, the coils 81a. are opposed to each other in their energization, and the coils 81 are opposed to each other, but each coil 81 acts in the same direction as the adjacent coil 810, on the same half of the core." Thus at any time the energization of the coils may produce a positive pole at a point between the coils 81a and a negative pole between the coils 81.

The movable magnetic core '71 may consist of a pair of substantially E-shaped members, each having a yoke 82, a pair of end legs 83, 84 and a centrally located leg 85. Each half of the movable core '11 may be energized by a winding 86, which is disposed about the central leg 85 inside of the outer legs 83, 84, and the windings 86 are opposed to each other when energized. The halves of the movable core 71 may be fixedly secured together by rivets and metal plates 90, and

- 7 if desired, the laminations may be staggered so as to be received between each other and secured by rivets.

The movable core '71 is preferably guided in its movement with respect to the frame 68 by some appropriate mechanism, such a plurality of links 87. 88, one end of each link being pivotally mounted on frame 68, and the other end being pivotally mounted on core 71, preferably at a point which is substantially in alignment with the center of gravity of the core for the purpose of eiire= inating strains upon the suporting links. Links 87, 88 may be provided at the front and back of the core 71 if desired, and it will be observe-:1 that parts of the core 71 are thus adapted to move to the left and right in Figure 8 upon the links 87, 88. Since the present form of linkagewould otherwise appear to be immovable, it will be observed that the lower links 88 have been provided with slots for rivets or pins 89, but as a matter of actual practice the ordinary looseness of the links and pins may be suflicient to permit the desired movement or vibration.

The width of the legs 78, 79, 83, 84, 85 is preferably such that appropriate air gaps 91, 92 are I left between the legs of the fixed core '30 and movable core '11, but the ends of legs 83, 84, 85 may be received together without an air gap.

The movable core '11 is preferably resiliently supported with respect to frame 68 by means of a plurality of springs 93, 94 interposed between frames 68 and parts of core '71, and'the springs 93, 94 are preferably located near the poles or ends of the legs 83, 84, 85,'so ,as to be most ef-=- fective in regulating the period of vibration and preventing the sticking together of the poles of the vibrator. Thus, the springs 94 may engage in relatively shallow sockets 98 in legs 83, 84, and the springs may react against a metal plate 95, which is adjustably supported by means of a rctatable screw bolt 98. The bolt 96 engages in a socket in frame 68 and in a threaded aperture in the plate 95, and the clockwise rotation of bolt 96 increases the compression of the springs 94, and vice versa. The springs 93, 94, are preferably so adjustedas to maintain the poles of the movable core 71 substantially midway between the poles of the fixed core '70, and the tension of the springs may be adjusted to vary the natural period of vibration of the vibrator to regulate its amplitude of vibration, and thus determine the force of the impulses given to the concrete form.

In some embodiments of the invention, the springs alone may constitute the means of sup-- port of the movable magnetic member upon the frame work. v

The coils 81, 86 may be energized by any'of the arrangements previously described, but one coil is preferably energized by direct current and the other bya pulsating or alternating current in order to produce mechanical vibrations of sufilcient strength to vibrate a concrete form.

Referring to Fig. 10, the vibrator illustrated in this figure, is that which is shown attached to the concrete form in Fig. 1, and this vibrator 'includes electromagnetic cores 2'? and 28 of substantially the same shape as those described with respect to Figs. 8 and 9, except that only one U- shaped core 2'7 and one E-shaped core 28 is emice ported in the casing 36 by means of a plurality of links 87, B8, pivotally mounted on casing 36 and pivotally connected to core 27 at the points 89 in substantial alignment with the center of gravity of core 27.

Thelegs 78, 79 of core 2'1 may be arranged between the legs 83, 84, 85, and substantially parallel thereto, and .the movement of the core 27 may be guided by securing non-magnetic strips of metal 97 to the legs 83, 84, 85 on both sides of the core 27 with sufiicient clearance to permit the core 27 to slide freely between strips 97.

The width of the legs of the core is also such that air gaps 91, 92 exist between the poles of the cores, and the movable core 27 may be resiliently engaged by springs 93, 94 at each side to regulate the period of vibration and maintain the movable poles substantially midway between the fixed poles upon deenergization of the magnetic circuit.'

The springs 93 are seated at one end in a socket 98 formed upon core 27, and at the other end in a metal plate or cup 95, which is fixedly mounted upon the end of a screw bolt 96. In the pres- .ent embodiment, the screw bolt 96 is threaded in the wall of casing 36 to adjust the tension of springs 93, 94. The casing 36 is fixedly secured to the diverging metal plates 30, 31 for convenient attachment to rounder fiat concrete forms.

The vibrator shown in Fig. 10 is peculiarly adapted to produce vibrations in a. vertical plane since the poles 78, '79 move upward and .downward with respect to the poles 83, 84, 85, and vertical vibrations appear to be peculiarly effective in the compacting or settling of concrete engagement with leg 85. Rubber block 100 may be secured in place by the use of a metal plate 101 and a plurality of screw bolts.

Referring to Fig. 11, this modified form of vibrator has a fixed armature 27 with a movable field core'28 of the type illustrated in Figs. 4 to 'l. The field core 28 is resiliently supported by an elongated metal spring 102, the central portion of which is secured to the back or core-28, and each end of which is provided with a curved portion 103 which is adapted to flex to permit the movement of core 28..

The curved portions 103 are again bent inward toward core 28 for securement to the frame or plate 31, and the ends 104 are provided with slots 105 for adjustably receiving the screw bolts 106.

The tension of springs 103 may be varied-by the position of the springs underneath the heads of bolts 106, and the core 28 is preferably arranged with the armature 27 located midway between the poles of core 28. Armature 27 may consist either of a permanent magnet or a magnetic member energized by direct current.

When the coils 60, 61 are energized with alternating current, the direction of the flux in the poles 50, 51 is periodically reversed and the poles are alternately attracted and repelled by armature 27; that is, when the pole 50 is attracted downward in Fig. 11, the pole 51 is also repelled as previously described. The resulting vibration oi the core 28 is substantially a rotary oscillation about the center of gravity of core 28, and the concrete form to which the plates 30, 31 are attached is subjected to corresponding mechanical vibration.

If desired, the present vibrator may be provided with stop means ior the purpose of limiting its amplitude, consisting of a pair of rubber blocks 143 interposed between poles 50, 51 and the supporting plate 31. a

Referring to Fig. 12, this is a vertical sectional view of a modified form of vibrator. This vibrator is preferably provided with the same diverging plates 30, 31, or other means for attachment of the vibrator to a form. .The relatively fixed magnetic member, which may be termed the core 109 may be fixedly secured by means of non-magnetic brackets 110 to the plates 30, 31. The brackets 110 may consist of sheet metal members having a pair 01' attaching fianges 111 and 112 extending substantially parallel to each other for attachment to the plates 30, 31 and core 109 by screws or other fastening means:

The core 109 may be provided with one or more coils or windings 113, which may be secured in place by engagement between the bodies of the Jorackets 110, and the core or armature 109 may thus be given a predetermined polarization by direct current energization or by any of the modes of energization described herein.

The field core 114 may consist of a substantially U-shaped member having a pair of legs 115, 116 joined by a yoke 117. The yoke 117 is provided with one or more coils or windings 118 for energizing the core 114, and the legs 115, 116 are spaced sufiiciently to receive the body 109 between them, leaving a small air gap 119 between each leg and the core 109 when the vibrator is not energized.

The core 114 may be provided with guides adjacent core 109 consisting of non-magnetic plates 120, such as brass plates, which are fixedly secured to core 114 on each side for slidably engaging core 109 and guiding the movement of core 114. Each leg 115, 116 is provided with a pair' of plates 120, and the thickness of core 109 with 120 respect to the legs 115, 116 should preferably be such that there is a slight degree of clearance between plates 120 and core 109, so that the core 114 may move freely.

The core 114 is preferably movably and resiliently supported with respect to the core 109, and for this purpose, the core 114 may be provided with a sheet metal casing 121, which is formed to receive the core 114 and coils 118, and which is provided with a pair of laterally projecting spring engaging flanges 122.

The structure for supporting each side of the casing 121 from the flanges 122, is identical, and consequently, only one 01' these devices need be described in full. The flange 122 is preferably provided with outwardly projecting tongues 123, forming shoulders for retaining a pair of springs 124, 125 in place, seated one .each side of flange 122.

The plates 30, 31 are preferably provided at their rear side with spring supporting members ?9 50 receive adjusting screws 132, which has ing polarization of said core adjacent said poles, and resilient means for holding said movable core in an intermediate position between said poles.

B. An electromagnetic vibrator, comprising a frame, a pair of oppositely disposed ma netic cores carried by said frame with an air gap between the poles of said cores, and a second magnetic core movable on said frame and having parts on opposite sides of each of said poles, windings carried by said latter core for producing polarization of said core adjacent said poles, resilient means for holding said movable core in an intermediate position between said poles, and means for adjusting the tension of said resilient means to vary the force of the vibrations.

7. An electromagnetic vibrator comprising a supporting frame, a pair of oppositely disposed ing for polarizing said armature and means for periodically reversing the polarity of said field structure to vibrate said frame.

9. An electromagnetic vibrator comprising'a magnetic core and a magnetic armature movably mounted with respect to said core, a source of alternating current, windings for said vibrator energized by said alternating current, whereby said armature is vibrated at a corresponding frequency with respect to said core, said wind- 'ings being located on said core, auxiliary wind-' ings carried by said armature, and a source of electromotive force for energizing said auxiliary windings to polarize said armature andincrease the power 0! said vibrations.

, 10. In an electromagnetic vibrator, the combination of a magnetic core having a pair of oppositely located poles, with an armature movably mounted between said poles, windings carried by said core and acting in the same direction to induce flux in said core, windings on said armature, and a source of electromotive force for energizing said armature windings to polarize said armature, and a source of alternating current for energizing said core windings, whereby said armature is made to vibrate at a corresponding frequency by said poles. g

11. In an electromagnetic vibrator, the combination of a magnetic core having a pair of oppositely located poles, with an armature movably mounted between said poles, windings carried by said core to induce flux in said core,

windings on said armature, a source of electromotive force for energizing said armature windingstopolarizesaid armaturaas'ourceof alternating current for energizing said core wind-' ings, whereby said armature is made to vibrate at a corresponding frequency by said poles, saidcoro windings comprising two parts oppomtely wound to induce flux in different directions, and rectiflers connected in circuit with said core wfidings, whereby each core winding is energisedbythehalf wave of alternating current.

12. A dynamic electromagnetic vibrating ap paratus comprising a substantially E-shaped core having two opposing poles located on opposite sides of a central pole, energizing windings carried by said core and adapted to polarize said core and a movable winding movably mounted on said central pole and adapted to react against said core, and a source of alternating current for energizing said movable windings, whereby corresponding vibrations are induced between said core and movable winding.

13. An electric vibrating apparatus for concrete forms, comprising a supporting plate for engaging a form, adjustable tension members adapted to be secured to the form and to draw said plate against said form, and a pair of relatively movable electromagnetic bodies mounted for reciprocation with respect to each other, one of said bodies being fixedly mounted on said plate, electric windings carried by one of said magnetic bodies, and a source of alternating current for energizing said windings, whereby direct me chanical vibrations are induced in said form.

14. An electric vibrator comprising a supporting frame with a pair of substantially U- shaped magnetic bodies mounted on said frame and forming a closed magnetic circuit, a second magnetic body movably mounted with respect to said frame and located intermediate the legs of said 'U-shaped bodies, and windings carried by the legs of said U-shaped magnetic bodies, and adapted to induce flux in opposite directions in each of said legs, whereby said closed magnetic circuit is polarized at points adjacent said second magnetic body.

15. An electric vibrator comprising a supporting frame with a pair of substantially U-shaped magnetic bodies mounted on said frame and forming a closed magnetic circuit, a second magnetic body movably mounted with respect to said frame and located intermediate the legs of said U-shaped bodies, windings carried by the legs of said U-shaped magnetic bodies and adapted to induce flux in opposite directions in each of said legs, whereby said closed magnetic circuit is polarized at points adiacent said second magnetic body, and resilient means for supporting said second magnetic body on said frame and preventing impact between said magnetic bodies.

18. An electric vibrator comprising a supporting frame with a pair of substantially U-shaped magnetic bodies mounted on said frame and forming a closed magnetic circuit, a second magnetic body movably mounted with respect to said frame and located intermediate the legs of said U-shaped bodies, windings carried by the legs of said U-shaped magnetic bodies and adapted to induce flux in opposite directions in each of said legs, whereby said closed magnetic circuit is polarized at points adjacent said second magnetic body, resilient means for supporting said second magnetic body on said frame and preventing impact between said magnetic bodies, and means for adjusting the tension of said resilient means for changing the vibrating characteristics of said vibrator.

1'7. In an electric vibrator, the combination of a support with a member of magnetic material fixedly mounted on said support, a winding about said magnetic member for-inducing flux in the same, a second magnetic member having a pair of poles located on opposite sides of said first mentioned magnetic member, a winding for inducing flux in said second magnetic member, resilient means for supporting said second magnetic member with respect to said first mentioned magnetic member and means for adjusting the tenr 1,932,520 I I p 9' sion of said resilient means to resist the movement of said second magnetic member and preventv impact between said magnetic members, one of said windings being energized by continuous current to polarize one of said magnetic members, and the other of said magnetic members being energized by alternating current whereby said second magnetic member vibrates with respect to the first, the amplitude being determined by the magnetic flux induced and the strength of the springs.

18. In a vibrating apparatus, the combination of a concrete form adapted to support a predetermined mass of concrete, with a pair of electromagnetic bodies, one of said electromagnetic bodies being fixedly secured to said form, and the other of said electromagnetic bodies being movably mounted with respect to said form, an energizing winding means associated with said electromagnetic bodies and adapted to. produce flux in said bodies, whereby relative vibration is produced between said bodies when said winding is energized with an electromotive force having a component of varying direction, said movable electromagnetic body having a predetermined proportion of mass relative to the mass of said form and concrete sufficient to induce mechanical vibration in said form and concrete by virtue of the inertia reaction of said movable magnetic body on said mass and concrete.

19. In a vibrating apparatus, the combination of a concrete form adapted to support a.predetermined mass of concrete, with a pair of electromagnetic bodies, one of said electromagnetic bodies being fixedly secured to said form, and the other of said electromagnetic bodies being movably mounted with respect to said form, an energizing winding means associated with said electromagnetic bodies and adapted to produce flux in said bodies, whereby relative vibration is produced between said bodies when said winding is energized with an electromotive force having a component of varying direction, said movable electromagnetic body having a predetermined proportion oi mass relative to the mass of said form and concrete sufficient to induce mechanical vibration in said form and concrete by virtue of the inertia reaction of said movable magnetic body on said mass and concrete, and resilient means for supporting said movable magnetic body with respect to the other magnetic body, said resilient means resisting relative movement of said magnetic bodies sufliciently to prevent impact of said bodies.

20. In a vibrating apparatus, the combination of a concrete form adapted to support a predetermined mass of concrete, with a pair of electromagnetic bodies, one of said electromagnetic bodies being fixedly secured to said form, and the other of said electromagnetic bodies being movably mounted with respect to said form, an energizing winding means associated with said electromagnetic bodies and adapted to produce flux in said bodies, whereby relative vibration is produced between said bodies when said winding is energized with an electromotive force having a component of varying direction, said movable electromagnetic body having a predetermined proportion of mass relative to the mass of said form and concrete suflicient to induce mechanical vibration in said form and concrete by virtue of the inertia reactionof said movable magnetic body on said mass and concrete, said apparatus including windings for direct current energization or one of said bodies and for alternating current energization of the other of said bodies.

21. In a vibrating apparatus, the combination of a concrete form adapted to support a predetermined mass of concrete, with a pair of electromagnetic bodies, one of said electromagnetic bodies being fixedly secured to said form, and the other of said electromagnetic bodies being movably mounted with respect to said form, an energizing winding means associated with said electromagnetic bodies and adapted to produce iiux in said bodies, whereby relative vibration is produced between said bodies when said winding means is energized with an electromotive force having a component of varying direction, said movable electromagnetic body having a predeter mined proportion of mass relative to the mass of said form and concrete sufiicient to induce mechanical vibration in said form and concrete by virtue of the inertia reaction of said movable magnetic body on said mass and concrete, one of said electromagnetic bodies being polarized and the other of said electromagnetic bodies being energized by alternating current, whereby 'gh frequency vibrations are produced of sub-.100 stantially the same frequency as said alternating current. I

22. In a vibrating apparatus, the combination of a concrete form adapted to support a predetermined mass of concrete, with a pair of electromagnetic bodies, one of said electromagnetic bodies being fixedly secured to said form, and the other of said electromagnetic bodies being movably mounted with respect to said form, an energizing winding means associated with said electromagnetic bodiesand adapted to produce fiux in said bodies, whereby relative vibration is produced between said bodies when said winding means is energized with an electromotive force having a component of varying direction, said movable electromagnetic body having -a predetermined proportion of mass relative to the mass of said form and concrete suflicient to induce mechanical vibration in said form and concrete by virtue of the inertia reaction of said movable magnetic body on said mass and concrete, said apparatus including windings for direct current energization of one of said bodies and for alternating current energization of the other of said bodies, one of said electromagnetic bodies being polarized, and the other of said electromagnetic bodies being energized by alternating current whereby high frequency vibrations are produced of substantially the same frequency as said alternating current, and means for adjusting the characteristics of said resilient means to vary the amplitude of vibration and the amount of power input. 23. In a vibrating apparatus, the combination of a concrete form adapted to support apredetermined mass of concrete, with a pair of electromagnet bodies, one of said electromagnetic bodies being fixedly secured to said form, and they other of said electromagnetic bodies being movably mounted with respect to said form, an energizing winding means associated with said electromagnetic bodies and adapted to produce flux in said bodies, whereby relative vibration is-produced between said. bodies when said winding means is energized with an elec- 45 tromotive force having a component of varying direction, said movable electromagnetic body having a predetermined proportion of mass relative to the mass of said form and concrete suflicient to induce mechanical vibration in said form and concrete by virtue oi the inertia reaction of said movable magnetic body on said mass and concrete, said form having a pair of angle irons oppositely disposed thereon, hook shaped members carried by flexible members attached to one of said. magnetic bodies, and force multiplying means for tensioning said flexible members to draw said latter electromagnetic body into fixed engagement with said form.

24. In a vibrating apparatus, the combination of a concrete form adapted to support a predetermined mass of concrete, with a pair of electromagnetic bodies, one 01 said electromagnetic bodies being fixedly secured to said form, and the other of said electromagnetic bodies being movably mounted with respect to said form, an energizing winding means associated with said electromagnetic bodies and adapted to produce flux in said bodies, whereby relative vibration .is produced between said bodies when said winding means is energized with an electromotive force having a component of varying direction, said movable electromagnetic body having a pre determined proportion of mass relative to the 'mass of said form and concrete sufflcient to induce mechanical vibration in said form and concrete by virtue of the inertia reaction of said movable magnetic body on said mass and concrete, and means for adjusting the characteristics of said resilient means to vary the amplitude oi vibration and the amount oi power input, said Iorm comprising a pipe term with axially extending angle irons, hook shaped mem--

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