Abstract:
A concrete vibrator which may be powered by a portable drill includes a housing having a contacting pad at one end and an axial bore. A camshaft is received within the bore. A transverse retainer is secured on the camshaft for retaining the camshaft within the axial bore. The camshaft is shaped to form a pair of cam surfaces at one end. A cam follower is disposed off center within the bore for engaging the cam surfaces when the camshaft is rotated. The cam follower and cam surfaces cooperatively cause axial reciprocation of the rotating camshaft within the bore for producing axial vibration of the housing face. The axial bore includes a radially expanded portion receive the retainer and prevent complete withdrawal of the camshaft. The camshaft includes a transverse bore for receiving the retainer within the radially expanded portion. The retainer has a spring bearing against a trapped ball projecting beyond the cylindrical surface of the camshaft.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is broadly concerned with a concrete vibrator apparatus. More particularly, it is concerned with a portable, hand held vibrator for use in conjunction with insulated concrete forms.  
         [0002]     Modern building techniques for construction of concrete walls in commercial and residential structures frequently employ insulated concrete forms (ICF). These forms are constructed of a plastic foam material such as expanded polystyrene, extruded polystyrene, polyurethane or cement-foam composites. The foams are inert, nonabsorbent, are superior insulators, having extremely high R-values per inch, and are good barriers against air and moisture. The foams are also lightweight and easy to form or cut into blocks and panels.  
         [0003]     Foam block units are generally of interlocking construction, which may be stacked into spaced-apart, open top walls which may be joined together using appropriate ties to produce hollow forms. Panel and plank units are stacked atop each other in parallel relation to form spaced-apart, open-top walls which may also be joined together using appropriate ties to produce similar hollow forms. Once constructed, the forms may be braced with wood and/or metal bracing members, and reinforcing rods placed therein. Concrete slurry is poured or pumped into the central cavity and permitted to cure, generally for about 48 hours. When the bracing is removed, the forms remain in place and are covered by interior and exterior finishing materials such as drywall, plaster, stucco, siding, brick or stone. This method of construction is increasingly popular because the finished structure is strong, durable, quiet, air tight and well insulated. Such structures are unusually energy efficient because the composite walls produce superior insulation qualities with reduced air infiltration.  
         [0004]     Clearly, the integrity of a structure consisting of a layer of concrete sandwiched between layers of an insulating foam skin is dependent on the homogeneity of the concrete core. Air pockets and bubbles can negatively affect all of the beneficial qualities of the concrete and, if they are sufficiently large in size, can compromise its structural integrity as well.  
         [0005]     Traditional concrete construction employs metal and/or wooden forms and such voids are commonly eliminated from wet concrete using a vibrator before the mix cures. In order to accomplish this, a worker often stands atop the form; inserts an elongated vibrator into the wet concrete between the rebar reinforcement rods and moves the vibrator up and down in the concrete between the forms to urge bubbles to the open surface. Such methods are generally not applicable to ICF construction because of the relative fragility of the plastic foam. Because the conventional vibrator must be elongated for reaching to the bottom of the wall structure, it is not easily controlled and may bump against the walls of the form. While wooden or metal form walls can withstand such rough handling, the more fragile foam forms may be punctured or displaced by vibrator contact. Foam forms are also subject to “blow outs” if subject to excessive bumping or rough handling, which might occur if a worker attempted to insert a vibrator shaft into the form from an adjacent scaffolding or ladder.  
         [0006]     Wall contacting vibrators are known in the prior art. However, they are generally too heavy or cumbersome for hand held use, require physical attachment at locations along the form and/or are likely to damage foam forms.  
         [0007]     Thus, there is a need for a concrete vibratory device having structure for contacting a foam wall and transmitting vibratory contact force; that can be moved along the exterior surface to remotely compact the concrete inside the form without form damage, and that is portable, light weight and hand held so that it can easily be controlled by a user.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides a greatly improved, handheld concrete vibrator which may be powered by a low-cost portable drill to compact concrete in an insulated concrete form (ICF) system. The assembly is portable, lightweight, simple in construction, and easily controlled for sweeping movement over the exterior surface of the form to work bubbles upwardly toward the open form top. The vibrator delivers an axial vibrating motion against the form that is distributed over a large surface so that it does not cause damage to the foam.  
         [0009]     The vibrator includes a housing of a suitable, low friction but rigid material such as a synthetic resin material having a face at one end and an axial bore. A camshaft is received within the bore. A transverse retainer is secured on the camshaft for retaining the camshaft within the axial bore while allowing axial displacement therebetween. The camshaft at one end is shaped to form a pair of cam surfaces. A cam follower is disposed off center within the bore for engaging the cam surfaces when the camshaft is rotated. The cam follower and cam surfaces cooperate to cause axial reciprocation of the rotating camshaft within the bore, for producing axial vibration of the housing face. The axial bore includes a radially expanded portion to receive the retainer and thereby prevent the camshaft from being completely withdrawn from the housing but permitting easy relative axial movement therebetween. The camshaft includes a transverse, threaded bore for receiving the retainer within the radially expanded portion. The retainer has a hollow, generally cylindrical interior containing a spring bearing against a trapped ball projecting beyond the cylindrical surface of the camshaft.  
         [0010]     Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.  
         [0011]     The drawings constitute a part of this specification and include an exemplary embodiment of the present invention, and illustrating various objects and features thereof. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a perspective view of a hand held concrete vibrator in accordance with the present invention, shown in use in conjunction with a portable hand held power drill for external vibration of a concrete mix contained within an insulated wall form.  
         [0013]      FIG. 2  is a perspective e view of the vibrator shown installed on a hand held portable drill.  
         [0014]      FIG. 3  is a perspective view of the concrete vibrator of  FIG. 1 .  
         [0015]      FIG. 4  is an enlarged sectional view of the housing taken along line  4 - 4  of  FIG. 3  showing the shaft and cam follower with the retainer removed.  
         [0016]      FIG. 5  is view similar to that shown in  FIG. 4  with a sectional view of the retainer and its bore.  
         [0017]      FIG. 6  is a view similar to that shown in  FIG. 5 , with the shaft rotated about 45 degrees and commencing to ride up on the cam follower.  
         [0018]      FIG. 7  is a view similar to that shown in  FIG. 5 , with the camshaft rotated 90 degrees and the top and riding up on cam follower.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.  
         [0020]     Referring now to the drawing figures, the reference numeral  1  refers to a hand held concrete vibrator  1  in accordance with the invention, which is depicted in  FIGS. 1 and 2  in association with a portable hand held drill  2  which is connected to the vibrator  1  for use in vibrating an insulated concrete wall form (ICF)  3  stabilized with bracing  4  and filled with a concrete mix  5  ( FIG. 1 ).  
         [0021]     As best shown in  FIGS. 3-7 , the concrete vibrator  1  includes a housing  10  having a vibration head or pad  11  at the free end, a hand piece or handle portion  12  at the inboard end and an axial bore  13 . The vibration pad  11  is generally cylindrical in shape, and includes a front surface or face  14 , rear surface  15  and circumferential sidewall  16 . The elongated handle  12  is axially aligned with the pad  11  and is also generally cylindrical in shape and includes a rear surface  21  and circumferential sidewall  22 . The diameter of the hand piece  12  is substantially less than the diameter of the pad  11  to enable comfortable circumferential gripping by a hand as shown in  FIG. 1 . The bore  13  is blind, extending axially from a countersunk entrance at the rear surface  21  of the handle  12  to the area of the junction of the handle  12  and the pad  11 .  
         [0022]     The housing  10  is of unitary construction from a synthetic resinous polymer material such as low or high density polyethylene, ultra high molecular weight polyethylene, a fluoropolymer, polypropylene, a metal such as aluminum or titanium or any other durable, fracture and abrasion resistant, lightweight material able to withstand rough handling. As shown in  FIGS. 1-4 , all of the edges of the housing  10  are rounded over for strength and to eliminate any edges that might catch on surface irregularities in the foam form  3  and impair the smooth movement of the apparatus  1  over the surfaces of the form  3 .  
         [0023]     An elongate, generally cylindrical drive or camshaft  23  is received within the bore  13  ( FIGS. 4-7 ). One end of the camshaft  23  is shaped or rounded to form a cam surface  24  and the opposite end includes a stub shaft  25  having a reduced diameter for reception in a drill chuck  31  ( FIG. 2 ). A center portion or shank  26  extends between the ends. A cam follower  32  ( FIGS. 4-7 ) is disposed within the axial bore  13 , and is positioned off center, adjacent the sidewall of the bore  13 . The cam follower  32  includes a cylindrical body portion  33 , with a curved head or top  34 . It is also foreseen that the axial bore  13  may include an apertured bearing plate for supporting the cam follower  32 . In such embodiments the cam follower  32  is threaded for registry with the bearing plate apertures and to permit adjustment of the depth of the cam follower  32  within the axial bore  13  by rotating advancement of the follower  32  within the apertures.  
         [0024]     The camshaft  23  and cam follower  32  are constructed of 440-C stainless steel or which is hardened by heat treating to a Rockwell hardness number of 62 for a working wear life of tens of millions of oscillations. It is foreseen that other anti-galling metal materials may also be employed. The follower head  34  preferably has a radius of about 3/16 inch. The cam surface  24  preferably includes a pair of bevels, each subtending an angle of about 45° and resulting in a profile in which the cam surfaces subtend an angle of about 90° with respect to each other. The apex or cam center  27  is curved to form a radius of about 3/16 inches, corresponding with the radius of the follower head  33 .  
         [0025]     A transverse threaded bore  35  extends through the shank  26  of the camshaft  23  for receiving a threaded retainer assembly  40  ( FIG. 4 ). The retainer  40  is of the ball detent or plunger type and includes a hollow, generally cylindrical housing  41  having an outwardly open end  42  terminating in a crimp or stop  43  which serves to reduce the diameter of the open end  42 . The crimp  43  traps a ball  44 , which is biased outwardly by a coil spring  45 . The base wall of the housing  41  is equipped with a slot  50  ( FIG. 5 ) to enable insertion and advancement of the retainer assembly  40  through the threaded bore  35  as well as selective adjustment of the retainer  40  until the ball  44  protrudes outwardly about 0.11 inches.  
         [0026]     The axial bore  13  includes a radially expanded bore portion  36  for receiving the retainer  40  and enabling free rotation of the protruding ball  44  as the shaft  23  is axially rotated. The radially expanded bore  36  also serves as a lubrication chamber and may be charged with a quantity of a heat resistant lubricant composition such as lithium grease.  
         [0027]     As best shown in  FIG. 1 , the vibrator apparatus is used in association with insulated concrete forms  3 , which include a series of generally rectangular foam insulation block units, panels or planks  6  having a series of spaced projections  51  along the top edge for mating engagement with corresponding spaced depressions (not shown) along the bottom edge of each form block, panel or plank  6 . The blocks, panels or planks  6  are placed atop prepoured footings or piers and are positioned and held in parallel relation by a series of generally H-shaped synthetic resin ties  52 .  
         [0028]     The bracing system  4  provides lateral support to the form  3  at intervals with a series of horizontal supports  53  and vertical masts  54 . Transverse bracing members  55  are attached to the supports  53  and/or masts  54  and are held in place on the ground by pegs  60  or other ground engaging means. While wooden bracing is depicted in  FIG. 1 , it is foreseen that the braces may also be of metal construction, such as C-channel stock. The horizontal, vertical and transverse members  53 ,  54  and  55  are intercoupled with each other by means of fasteners such as nails, screws or turnbuckles, and the masts  54  may also be fastened to the ties  52 . Steel reinforcing bar members (not shown) are installed within the cavity in the form  3 , and the form is filled with a concrete mixture  5 . The number and size of air bubbles present in the form at the conclusion of the pour will vary depending upon the size of the aggregate and the slump, with a 6 inch slump being generally preferred.  
         [0029]     In use, the vibrator apparatus  1  is installed on a portable hand drill  2  in the manner shown in  FIG. 2  by installing the stub shaft  25  into the drill chuck  31  and tightening the chuck  31 . An exemplary drill is a ½ inch portable battery operated hand drill manufactured under the trademark Dewalt®, although any other chucking drill motor may be employed. On high drive, such a drill will deliver about 1800 revolutions per minute (rpm). A user actuates the drill, which drives the camshaft  23 , causing it to rotate axially within the bore  13  through a motion cycle in which the cam  23  rides in and out over the fixed follower  32 . It is foreseen that other means for rotating the shaft  23 , such as a motor may be substituted for the portable hand drill  2  and that the motor means and vibrator  1  may be of unitary construction or in a single unit.  
         [0030]      FIGS. 5-7  depict rotation of the cam  23  through the return portion of a motion cycle in which the cam center  27  moves toward the fixed follower. In  FIG. 5 , the cam  23  is positioned at its lowest point in the bore  13 , with the follower  32  farthest away from the cam center  27 . In  FIG. 6 , the cam  23  has rotated clockwise from the position shown in  FIG. 5  causing return of the cam center  27  toward the follower  32  and riding up of the cam  23  within the bore  13 . In  FIG. 7 , the cam  23  has rotated clockwise  900  from the position shown in  FIG. 5  to a dwell position in which the cam  23  is at rest atop the follower  32  and the cam is positioned at its highest point in the bore  13 . Because the camshaft includes two cam surfaces  24 , each full 3600 revolution of the camshaft  23  completes two full motion cycles of the cam  23 . Thus, actuation of the drill at about 1800 rpm causes oscillation of the cam  23  within the bore at about 3600 oscillations per minute.  
         [0031]     As shown in  FIG. 1 , a user  61  grasps the handgrip portion  12 , positions the contacting pad  11  normal to the surface of the form  3  and actuates the drill  2 . This produces a uniform density filling of concrete  5  within the form  3 . The axial movement of the cam  23  as it is rotated by the drill  2  is normal or perpendicular to the surface of the form  3 . Advantageously, imparting this shaking movement to the foam panels  6  causes the concrete mix  5  to be agitated within the form  3 . This in turn allows any bubbles present within the mix  5  to consolidate and move upwardly toward the surface of the mix  5 . By commencing at the bottom area of the form  3 , and working upwardly, a user  61  can urge the bubbles upwardly with the greatest efficiency. This method is particularly effective in removing bubbles in areas generally hard to reach such as corners and window and door openings, which tend to impede the flow of concrete during the pour and to collect bubbles. Those skilled in the art will appreciate that the vibrator apparatus  1  may also be used in connection with a hand drill  2  or other means for rotating the shaft  23  to compact any of a number of materials, whether or not they are contained within a form  6 . For example, the apparatus may be employed to compact soil or sand.  
         [0032]     It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.