Abstract:
A grinding machine abrasive unit holder with the use of springs, gases or fluids allows each abrasive unit to be in contact with the floor, independently at all times. This action allows the finishing of the high and low spots of the floor in the same operation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation in part application of U.S. patent application Ser. No. 10/900,786 filed Jul. 28, 2004 which is pending. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention is related to a system for polishing concrete. More particularly, the present invention is related to a system, and method, for polishing concrete without the typical problems of uneven polishing in the valleys and hills of poured concrete.  
         [0003]     Polishing concrete has been known for some time. The abrasive units of floor grinding machines are typically rigidly attached to the drive mechanism of the machine thus allowing the abrasive units to operate in a single plane. Despite the most skilled of floor finishers concrete floors are not perfectly flat. A typical technique for polishing concrete will be described with reference to  FIG. 1 .  
         [0004]     In  FIG. 1 , the concrete floor,  1 , is uneven with valleys,  2 , and hills,  3 . The concrete floor,  1 , is polished by rotating and translating a plate,  5 , with abrasive units,  4 , rigidly attached thereto. As the plate is rotated and translated the abrasive units grind away concrete to remove rough portions. As can be seen from the illustration of  FIG. 1 , the valleys,  2 , do not readily come into contact with the abrasive unit and therefore are not polished. This leaves an unsightly floor with portions polished and other portions rough. To avoid this, the operator typically starts with a very course abrasive unit with the desire being to decrease the height of the hills,  3 , till they are even with the valleys,  2 . Less course abrasive units are then used to finish polish the floor. This method has several disadvantages.  
         [0005]     Course abrasive units remove a substantial amount of concrete to eliminate any hills. Often this exposes aggregate, or rock filler, in the concrete. As the polishing continues those areas that were originally in a valley are not polished or grinded to the same degree and the aggregate is therefore not exposed. The end result is a floor with some portions having exposed aggregate and other portions not having exposed aggregate. This is unsightly.  
         [0006]     Yet another problem with the prior art is the high cost associated with time and material for the polishing or grinding process. Multiple polishing operations are required with each using successively less course abrasive units. The multiple operations are time consuming. The course abrasive units typically create scratches, or gouges, in the concrete which must be removed with the less course abrasive unit. In many instances the final floor still has scratches and gouges since it is very difficult to remove them all with the time and resources typically allotted for such an operation.  
         [0007]     Yet another problem is the loss of abrasive units due to breakage. As the abrasive unit crosses a valley and reengages with a hill it is not uncommon for parts of the abrasive unit to become dislodged or broken. This damage greatly decreases the useful lifetime of abrasive units.  
         [0008]     There has been a long felt desire for a floor polishing system which can effectively polish a floor without regard for hills and valleys and the differential grinding required to polish both.  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to provide a flexible mounting of the abrasive unit that will allow for finishing of concrete floors without the need to grind the high spots to a lower level.  
         [0010]     It is another object to provide an abrasive unit, and holder, which can be attached to a conventional plate. The method of attachment allows the holder to “float” or move in a vertical direction thereby allowing the abrasive unit to contact the floor at all times and everywhere.  
         [0011]     A particular feature of the present invention is that the high spots, or hills, do not have to be ground down to the level of the low spots, or valleys, thereby achieving a uniform appearance which is aesthetically pleasing.  
         [0012]     Another particular advantage is a substantial savings in time and labor. Larger floor areas can be completed in a given time period.  
         [0013]     Yet another advantage is the increased longevity of the improved abrasive units.  
         [0014]     Yet another advantage is the elimination of multiple passes with successively decreasing coarseness. This advantage is due to the elimination of the necessity to decrease the height variations in the floor. A concrete floor can be rendered smooth and aesthetically pleasing in a single pass with a low coarseness abrasive unit.  
         [0015]     These and other advantages, as will be realized, are provided in a floor polisher with a rotating plate, a multiplicity of variable vertical displacement mounting devices attached to and plate, and an abrasive unit attached to each vertical displacement mounting device.  
         [0016]     Yet another embodiment is provided in an abrasive unit particularly adaptable for use with a floor polisher. The abrasive unit has a cylindrical abrasive head and a frustoconical mounting head.  
         [0017]     Yet another embodiment is provided in a floor polisher with a rotating plate, a multiplicity of variable vertical displacement mounting devices attached to the plate and an abrasive unit attached to each vertical displacement mounting device. In the improvement the abrasive unit has a cylindrical abrasive head and a frustoconical mounting head.  
         [0018]     Yet another embodiment is provided in a floor polished with a rotating plate, a multiplicity of leaf springs attached to the plate and an abrasive unit attached to each leaf spring. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is an illustration of the prior art with fixed abrasive units.  
         [0020]      FIG. 2  is a partial cutaway view of a floor polisher.  
         [0021]      FIG. 3  is a side view of an embodiment of the present invention.  
         [0022]      FIG. 4  is a bottom view of the embodiment of  FIG. 3   
         [0023]      FIG. 5  is a partial cutaway view of an embodiment of the present invention.  
         [0024]      FIG. 6  is a perspective view of an abrasive unit of the present invention.  
         [0025]      FIG. 7  is a bottom view of an embodiment of the present invention.  
         [0026]      FIG. 8  is a partial cutaway side view of an embodiment of the present invention.  
         [0027]      FIG. 9  is a bottom view of an embodiment of the present invention.  
         [0028]      FIG. 10  is a partial cutaway side view of an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]     The invention will be described with reference to the various figures. The figures represent part of the present disclosure but are not intended to limit the scope of the invention. Within the various figures similar elements will be numbered accordingly.  
         [0030]     A floor polisher is illustrated in  FIG. 2 . In  FIG. 2 , the floor polisher,  10 , comprises abrasive units,  4 , mounted on a plate,  5 . A motor,  6 , rotates the plate,  5 . An operator then moves the floor polisher,  10 , across the floor by grasping the handle,  8 . The combination of the rotating plate and movement of the floor polisher allows the entire surface area to be polished. An optional shroud,  7 , assists in decreasing the dust emanating from under the floor polisher. An optional vacuum dust collection system,  11 , can be employed as known in the art.  
         [0031]      FIG. 3  is a partial side view of the present invention. In  FIG. 3 , the plate,  5 , has mounted thereon a multiplicity of variable vertical displacement mounting devices for the abrasive units,  4 . In  FIG. 3 , the variable vertical displacement mounting device comprises a spring,  9 , preferably a leaf spring, which is secured between the plate,  5 , and abrasive unit,  4 . Each abrasive unit can move vertically independent of each other abrasive unit. As a particular abrasive unit encounters a valley the downward force of the leaf spring is sufficient to force the abrasive unit into the valley. As a hill is encountered the abrasive unit can rise in opposition to the spring thereby eliminating any sudden impact with the hill.  
         [0032]     It is preferably that the abrasive unit,  4 , be received by an abrasive holder,  12 , which will be described further herein. A mounting bracket,  13 , is preferred for securing the leaf spring,  9 , to the plate,  5 . A mounting bracket,  14 , is also preferred for securing the abrasive holder,  12 , to the spring.  
         [0033]     A plate with three abrasive assembly units is shown from bottom view in  FIG. 4 . The three abrasive assembly units each comprise an abrasive element,  4 , and a variable vertical displacement mounting device in the form of a leaf spring,  9 . A holder,  12 , secures the abrasive unit to the spring. The variable vertical displacement mounting device is preferably secured to the plate by fasteners,  18 , such as threaded members, studs, welds and the like.  
         [0034]     In a particularly preferred embodiment the abrasive unit trails the location of the mounting of the spring to the plate. For example, with the device illustrated in  FIG. 4 , the direction of rotation is given by arrow,  15 . The abrasive unit,  4 , is in a trailing position relative to the spring,  9 . This configuration is preferred based on the realization that an obstruction is more easily overcome than if the abrasive unit leads the spring.  
         [0035]     The leaf spring strength is selected to be sufficiently strong to support the weight of the floor polisher at a sufficient height that the abrasive unit end of the spring does not contact the plate in normal use. It is also important that the spring be sufficiently displaced by the weight of the floor polisher to maintain the abrasive unit in a substantially planar relationship with the floor. It would be apparent from the description that as the abrasive unit moves vertically in response height variations in the floor the angle of the abrasive unit is slightly altered. Within the range of travel typically employed in the present invention the deviation from planarity is acceptable.  
         [0036]      FIG. 5  is a partial view of the variable vertical displacement mounting device of  FIGS. 3 and 4 . The abrasive unit is illustrated separately in  FIG. 6 . The abrasive unit,  4 , comprises an abrasion head,  16 , with a frustoconical base,  17 . The frustoconical base,  17 , is received by a mating frustoconical void,  19 , in the holder,  12 . The frustoconical base allows the abrasive unit to be easily placed in the holder and yet, due to surface resistance, prohibits the abrasive unit from being easily dislodged. The combination of a frustoconical base and a mating frustoconical void allows ease of replacement and eliminates the possibility of dust settling between the pieces. Dust between two moving pieces is preferably avoided since this renders the parts difficult to separate. By inserting and twisting the abrasive unit is sufficiently secured in the void to eliminate displacement. The abrasive unit can be removed by twisting and withdrawing the abrasive unit from the void. Fasteners,  18 , secure the optional bracket,  14 , through the spring,  9 , to the abrasive holder,  12 .  
         [0037]     An alternate embodiment is shown in bottom view in  FIG. 7  and partial cutaway side view in  FIG. 8 . The device comprises a plate,  5 . Mounted to the plate is the variable vertical displacement mounting device. The variable vertical displacement mounting device comprises a abrasive unit retainer,  21 . The abrasive unit retainer,  21 , allows the abrasive unit,  4 , to move vertically with a coil spring,  22 , biased to force the abrasive unit outward to the furthest extent allowed. Contact between a retainer shoulder,  23 , and an abrasive shoulder  24 , limit the furthest extent of the abrasive holder. Fasteners,  25 , secure the abrasive unit retainer,  21 , to the plate,  5 . The abrasive unit retainer allows independent vertical movement of the abrasive units with the coil spring,  22 , biased to extend the abrasive unit into a valley when encountered while the abrasive unit compresses the coil spring when encountering a hill.  
         [0038]     The coil spring is selected to be sufficiently compressed by the weight of the floor polisher such that the abrasive unit can travel downward the length of standard valleys without the ledges restricting further movement. The coil spring is also sufficiently strong that the abrasive unit does not contact the plate or any structure which limits the upward movement when the full weight of the floor polisher is placed upon the multiplicity of abrasive units. With properly chosen coil springs each abrasive unit is in contact with the floor and the floor polisher is suspended by the coil spring.  
         [0039]     Another alternate abrasive unit mounting is shown in bottom view in  FIG. 9  and partial cutaway cross-sectional view in  FIG. 10 . The embodiment comprises a plate,  5 . Mounted to the plate is the abrasive unit holder,  21 . The abrasive unit  4  moves vertically within the holder,  21 . Shoulders,  31 , within the holder,  21 , and shoulders,  32 , on the abrasive unit,  4 , control the distance the abrasive unit  4  is allowed to travel. The force of fluid,  33 , allows for the independent movement of the abrasive unit holder. An o-ring seal,  34 , and a piston seal,  35 , on the abrasive unit  4  seal the fluid,  33 , within the holder,  21 . All of the holders,  21 , on the plate,  5 , are interconnected via tubing,  36 , which allows the fluid to flow between them, maintaining equal pressure on all abrasive units,  4 , at all times. At rest the fluid insures that an equal pressure is placed on all four abrasive units. If a valley is encountered by one abrasive unit the increased weight on the three remaining abrasive units forces fluid toward the abrasive unit encountering the valley which automatically extends the abrasive unit into the valley. An abrasive unit encountering a hill would have increased pressure and the fluid flow is towards the three remaining abrasive units.  
         [0040]     The abrasive units typically comprise an abrasive material in a binder and a base. The abrasive material is preferably selected from diamond, silicon carbide, aluminum oxide and E.C. Diamond is the most preferred abrasive.  
         [0041]     The binder material is chosen, in part, based on the size of the abrasive particles. Particularly preferred binders include sintered bond, electroplate bond, vacuum brazed bond, epoxi bond, resin bond, phenolic bond and E.C. The most preferred binder materials are sintered bond, vacuum brazed bond, phenolic bond and resin bond.  
         [0042]     The abrasive units are typically classified by courseness with the higher number representing a finer abrasive material and a lower number representing a larger abrasive material. As would be realized, the larger the abrasive material the more aggressive the abrasive unit will be with regards to concrete removal. A particular feature of the present invention elimination of the necessity for aggressive abrasive units. In the prior art the aggressive abrasive units are necessary to decrease the variation described herein as hills and valleys. With the present invention a fine particle abrasive unit can be employed initially thereby greatly reducing the effort and greatly decreasing the time and cost of obtaining a smooth floor which is also more aesthetically pleasing.  
         [0043]     Yet another advantage with the present invention is the long life of the abrasive unit. Eliminating the collision between the abrasive unit and a hill, as described previously, increases the lifetime of the abrasive unit. Larger particle, more aggressive, abrasive units are also more fragile due to the decrease in the ratio of binder to abrasive material and they are therefore also more likely to encounter hills since it is at the early stage that these abrasive units are used. Therefore, the present invention provides a substantial cost benefit which is not otherwise achievable in the art.  
         [0044]     The invention has been described with particular emphasis on the preferred embodiments. It would be apparent from the description, discussion and ability of one with ordinary skill in the art to provide alternate embodiments and uses without departing from the scope of the invention as set forth in the claims appended hereto. It is contemplated that the invention could be used with other surfaces such as walls, ceilings, tiles, etc.