Abstract:
A clamping mechanism particularly for clamping a vibrator to a reinforcing bar. The clamping mechanism provides a slot which intersects a channel. The channel is longitudinally open in one direction at one side of said intersecting slot and longitudinally open in the opposite direction at the other side of said intersecting slot. A reinforcing bar or other member to be engaged first enters the slot then moves into the channel. Once in the channel, the bar or other member is positively retained therein.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 60/774,400, filed Feb. 17, 2006, and incorporates same by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a clamping mechanism and is particularly concerned with the clamping of a vibrator to a reinforcing bar. 
         [0003]    In the construction industry, it is frequently necessary to lay a large area of concrete. Such areas can include, for example, foundations for buildings, floors, driveways, columns, walls, ramps, etc. 
         [0004]    Concrete is a mixture of cement, sand, and stones, Lime is an ingredient in cement, and water is mixed with the components of the mixture to activate the lime and form a mix or slurry. Concrete exhibits characteristics of strength in compression but is relatively weak in tension. 
         [0005]    To increase strength in tension, it is common practice to prepare a grid of reinforcing bars (“rebars”) and then to pour concrete over and around the grid, so that the reinforcing bars improve the tension strength of the poured concrete. After the wet concrete has been poured over and around the grid of reinforcing bars, it is common practice in the art to vibrate the concrete to remove air and voids from the poured mix. In this manner, when the concrete hardens, the slab will be more compact and undesirable pockets within the hardened concrete are avoided, without compromising the integrity of the concrete. 
         [0006]    The most common form of concrete vibrator comprises a metal cylinder within which a shaft carrying an eccentric weight is rotatable to cause the metal cylinder to vibrate. The cylinder is mounted on one end of a flexible drive which serves to rotate the shaft and hence vibrate the cylinder. When the vibrating cylinder is introduced into, and immersed in, the wet concrete mix or slurry, vibrations—which may be in the region of 10,000 per minute—agitate the slurry to an extent sufficient to remove air and voids from the slurry. 
         [0007]    Another method involves imparting vibrations to the slurry through vibrating the reinforcing bar themselves. Top-mounted vibrators are described in U.S. Pat. No. 6,950,011 and JP 07048927. But these vibrators have certain problems. If a reinforcing bar is too tall—for example, it projects a distance above scaffolding—it is too high for the vibrator operator to reach the top of the bar and the vibrator cannot be mounted for use. A top-mounted vibrator also cannot be used if the end of the reinforcing bar is bent or hooked. Also, if a plurality of reinforcing bars are incorporated in a grid, there may be no individual bars with upwardly projecting ends for mounting in a vibrator. 
       SUMMARY OF THE INVENTION 
       [0008]    It has therefore been found desirable to mount a vibrator laterally on the side of a reinforcing bar or on such a bar incorporated in a grid. A quick engagement/release mechanism enables an operator to switch the vibrator from bar to bar in an assembly of bars or grid and thereby impart vibrations through an area of slurry. 
         [0009]    According to the present invention, there is provided a clamping mechanism including a frame, a channel within said frame, and a slot extending across said frame and intersecting said channel, said channel being longitudinally open in one direction at one side of said intersecting slot and longitudinally open in the opposite direction at the other side of said intersecting slot whereby an elongated member can be positioned in said slot and said clamping mechanism then turned in a direction in which portions of said elongated member on opposite sides of said slot respectively pass through the longitudinal open portions of the channel to a position in which the elongated member lies in and longitudinally along said channel. 
         [0010]    According to a further aspect of the invention, there is provided a vibrator attachable to a bar, said vibrator including a casing, means within said casing for vibrating said casing, and a clamp associated with said casing for engaging a bar, said clamp including a frame, a channel extending longitudinally through said frame, a slot extending across said frame and intersecting said channel at a location intermediate the ends thereof, said channel being longitudinally open in one direction at one side of said intersecting slot and longitudinally open in the opposite direction at the other side of said intersecting slot, said channel, said channel openings, and said intersecting slot all being dimensioned to accommodate said bar whereby said slot can be seated over said bar to adopt a position in which said bar lies across said channel whereupon the frame encompassing the elongated channel can be rotated in a direction in which a portion of the bar to one side of the slot passes through the longitudinal channel opening on said one side of the slot and a portion of the bar to the opposite side of the slot passes through the oppositely directed longitudinal channel opening on the opposite side of the slot to a position in which said bar lies in and along said channel within the frame. 
         [0011]    According to a still further aspect of the invention, there is provided a method of preparing a concrete structure including the steps of forming an area to confine the structure, positioning at least one reinforcing bar in the confined area, pouring a concrete slurry into said confined area to surround and partially envelope said at least one reinforcing bar, engaging said at last one reinforcing bar by a vibrator according to claim  3  such that said bar lies in the slot and across the channel, rotating said vibrator to move said engaged bar from said slot into said channel, orienting said vibrator to create an interference hold between the channel walls and the bar, and activating said vibrator to vibrate said at least one reinforcing bar and impart vibrations into the surrounding slurry. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention will now be described with reference to the accompanying drawings in which: 
           [0013]      FIG. 1  shown an exploded view of a vibrator; 
           [0014]      FIG. 2A  shows a perspective view of a housing of the vibrator; 
           [0015]      FIG. 2B  shows a perspective view of an insert accommodated in the vibrator housing; 
           [0016]      FIG. 2C  shows an exploded view of the vibrator housing shown in  FIG. 2A  with the insert shown in  FIG. 2B  in position; 
           [0017]      FIG. 3  shows a first step in the mounting of the vibrator on a reinforcing bar; 
           [0018]      FIG. 4  shows a subsequent step of the mounting of the vibrator on the reinforcing bar; 
           [0019]      FIG. 5  shows a front elevation of the vibrator mounted on the reinforcing bar. 
           [0020]      FIG. 6  shows a side elevation of the vibrator mounted on the reinforcing bar; and 
           [0021]      FIG. 7  shows a rear elevation of the vibrator mounted on the reinforcing bar. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0022]    Referring now to the drawings, and specifically to  FIG. 1 , a vibrator  10  includes a housing  30  including a cylindrical vibration portion  32  and a clamping portion  31 . In the preferred embodiment, most clearly shown in  FIGS. 2A and 2C  of the drawings, the cylindrical vibration portion  32  and the clamping portion  31  are two parts of an integral casing. However, the cylindrical portion  32  and the clamping portion  31  could be separate components secured to each other. Such separate components could be secured to each other by, for example, mating keyways, bolts, rivets, or like fasteners. However, in operation, the vibrator vibrates on the order of 10,000 vibrations per minute and separate components could, in some circumstances, create problems. Thus, in the preferred embodiment the cylindrical portion and the clamping portion are an integral unit, and the unit could be an integral casting of, for example, aluminum or the two component portions could be permanently welded together. The actual vibrating mechanism is, essentially, of conventional construction and vibrations are caused by rotating an eccentric weight at high speeds. 
         [0023]    To this end, the vibrating mechanism includes a rotatable shaft  26  disposed coaxially within the cylindrical vibration portion  32 . Bearings  22  and  24  accommodated within the cylindrical portion permit free rotation of the shaft therewithin, and an eccentric weight carried by the shaft will impart vibrations to the housing  30  when the shaft  26  is rotated at high speed. The eccentric weight  28  can be keyed or otherwise secured on the shaft or, preferably, the shaft can comprise two or more axially aligned coupled segments and the eccentric weight can be a unitary casting with one such segment. 
         [0024]    The shaft and eccentric weight are rotatable at speeds of the order of 10,000 revs per minute by an external power source (not shown) which is connected to the rotatable shaft by a flexible drive  14  coupled to the drive shaft  26  via a coupling  36 . The coupling  36  seals one end of the cylindrical portion  32  and protects the bearing  22 . The opposite end of the cylindrical portion  32  is closed by a cap  38  which similarly seals the remote end of the vibrator housing and protects the bearing  24 . In the embodiment shown in the drawings, the coupling  36  and cap  38  are provided with respective screw-threaded portions  36 a and  38 a which engage with mating threaded portions (not shown) at opposite ends of the interior of the cylindrical portion  32 . 
         [0025]    With the operational high rate of revolutions and the vibrations imparted thereby, heat generation has to be addressed and a plurality of cooling fins are provided to dissipate the heat generated. These cooling fins  33  are shown in  FIG. 1  (but, for clarity, omitted from  FIGS. 2A and 2C ) extending along the length of the cylindrical portion  32  and projecting radially therefrom with intervening spaces therebetween. 
         [0026]    The above-described vibrator is attachable to a reinforcing bar  12  by a quick clamping mechanism which will now be described in detail. 
         [0027]    The clamping portion  31  is best shown in  FIG. 2A  of the drawings and, as described in the preceding paragraphs, is preferably a unitary casting with the cylindrical portion  30 . The clamping portion  31  comprises a box-like frame having a base  40  adjacent the cylindrical portion  32 , side wall portions  41 ,  42  upstanding from said base, and a top portion  43 . The base, side wall portions, and top portion are shown respectively disposed at right angles to each other and define a rectangular channel dimensioned snugly to accommodate a firm but resilient insert  44 . It will be appreciated that both the frame and the reinforcing bar are metallic and the provision of an intervening resilient insert avoids having metal on metal in an environment subjected to high frequency vibrations. The insert is preferably a molding of urethane or similar polymeric material and, in addition to being snugly seated within the channel, is preferably secured in position by fasteners  45 . In the embodiment shown in the drawings, the fasteners are bolts which extend through the side wall portions of the frame and through mating bores in the insert. It will, however, be appreciated that secure fastening could be achieved by means other than bolts extending through the side walls and could, for example, include screw-threaded fastening plugs extending through the top portion  43  into the insert  44 . Whatever the form of fasteners used to secure the insert, the insert will be interchangeable and can readily be replaced by a new insert when worn by the operational vibrations. 
         [0028]    A slot  46  extends through the top portion  43  and down and part way through the side wall portions  41  and  42 . In the embodiment shown in the drawings, the slot  46  is shown extending at an angle across and through the top portion and, although the slot could extend transversely across the top portion (i.e., at right angles to the side portions  41 ,  42 ) an angle in the range from 15 degrees to 45 degrees from the transverse is preferred, since orientation of the slot at an acute angle will reduce the extent to which the vibrator must be rotated to seat a reinforcing bar in a channel in the insert in the manner described in the following paragraphs. 
         [0029]    The slot terminates part way through the side portions  41  and  42  and, from the lowermost extremity of the slot  46 , a further slot  47  extends longitudinally through the side wall portion  41  to the end of the rectangular channel adjacent the cap  38  and a similar slot  48  extends longitudinally through the side wall portion  42  to the end of the channel adjacent the coupling  36 . 
         [0030]    This arrangement of slots  46 ,  47 , and  48  results in the channel being longitudinally open in one direction in one side wall from one side of the slot  46  and longitudinally open in the opposite direction in the opposite side wall from the other side of the slot  46 . 
         [0031]    The insert  44 , best shown in  FIG. 2B  of the drawings, is a block of material similarly configured with a slot  50  extending from one side thereof partway through the block towards the other side to intersect a channel  51  extending longitudinally through the block. That channel  51  is open in one direction to mate with the slot  47  in the side wall portion  41  of the frame and, from the slot  50 , is open in the opposite direction to mate with the slot  48  formed in the other side wall portion  42  of the frame. 
         [0032]    The manner of attaching the vibrator to a reinforcing bar will now be described. 
         [0033]    The vibrator  10  is attached to the flexible drive  14  by means of the coupling  36  and, with the remote end of the flexible drive  14  connected to a power source, is ready for use. An area of concrete to be set has already been prepared by assembling forming to confine the area, the reinforcing bar or grid of reinforcing bars has been assembled and emplaced within the area and liquid concrete slurry has been poured into the confined area around the reinforcing bar or bars. The area to be cast can be any typical in the construction industry including, but not limited to, a floor slab, a wall, a ramp, a step or steps, etc. 
         [0034]    The vibrator is then mounted on a reinforcing bar, either an individual bar or a component or a grid of such bars, in the following manner. The bar or grid component does not necessarily have to be upright or transversely extending to receive the vibrator but can be oriented in any desired direction. 
         [0035]    The hand-held vibrator is introduced to the bar by passing the bar into and through the slot  46  to lie against the bottom of the slot in the manner shown in  FIG. 3  of the drawings. Thereupon, the vibrator is oriented or rotated in a clockwise direction, still with respect to  FIG. 3 , in which the upper portion  12   a  of the bar  12  enters and passes through the slot  48  in the side wall portion  42  of the frame and the lower portion  12   b  of the bar similarly enters and passes through the slot  47  in the side wall portion  41 .  FIG. 4  of the drawings shows the vibrator during this orienting or rotating step with the respective portions  12   a  ,  12   b  of the reinforcing bar entering and passing through the slots  48 ,  47 . 
         [0036]    As the rotation of the vibrator is continued the upper portion  12   a  of the reinforcing bar will pass into the channel  51  in the insert  44  which is firmly retained in the frame, and the bottom portion  12   b  of the reinforcing bar will similarly pass into aligned channel  52  in the insert  44 . When the reinforcing bar portions  12   a  ,  12   b  abut or lie along the bottoms of the respective channel portions there can be no further orientation or rotation of the vibrator which is thus firmly seated on the reinforcing bar. 
         [0037]    It is then only necessary to ensure firm retention of the vibrator thus mounted on the reinforcing bar and ensure not only that the vibrator does not slip up or down the bar but that the retention is sufficiently firm to prevent any chatter caused by the high-frequency vibrations generated by the vibrator. This could be accomplished by providing locking means in the form of a thumbscrew extending through one of the side wall portions  41 ,  42  or top portion of the frame or providing an equivalent lever operated cam locking arrangement. Although such locking means (not shown) would accomplish the desired result, the provision of such means would detract from the simplicity and easy operability of the clamping mechanism of the invention. The preferred method of firmly retaining the mounted vibrator on the reinforcing bar is by hand holding the flexible drive and applying a force to tilt the mounted vibrator away from the reinforcing bar in the manner most clearly shown in  FIG. 5  of the drawings. This tilting of the mounted vibrator will cause an interference jamming by opposing side wall portions of the insert channels  51 ,  52  on the reinforcing bar. 
         [0038]    In the embodiment shown in the drawings, the channels  51 ,  52  are straight-sided with rounded bottoms. The channels, however, could be keyhole-shaped in cross section or, preferably, vee-shaped. An advantage of vee-shaped channels having tapering side walls is that it can accommodated reinforcing bars of different diameters since the smaller the diameter the further the bar will penetrate the channel but will still firmly contact the tapering walls not only to provide an interference fit but also to eliminate or minimize chatter. 
         [0039]    Although the embodiments of the clamping mechanism described and shown in the drawings have particular relevance to the clamping of a vibrator on a reinforcing bar, it will be appreciated that the “slot and channels” arrangement is suitable for use in other fields where it is designed to clamp a component on to an elongated member regardless of the orientation of such member. Thus, the member can be, for example, standing upright or lying in a transverse direction.